docs: update documentation for v0.4.0 release

- Update README.md with v0.4.0 features and screenshots placeholders
- Update architecture.md with v0.4.0 implementation status
- Update progress.md marking all 27 tasks as completed
- Create CHANGELOG.md with complete release notes
- Add v0.4.0 frontend components and hooks

frontend/src/components/ui/badge-variants.ts

@@ -0,0 +1,21 @@
+import { cva } from "class-variance-authority"
+
+export const badgeVariants = cva(
+  "inline-flex items-center rounded-full border px-2.5 py-0.5 text-xs font-semibold transition-colors focus:outline-none focus:ring-2 focus:ring-ring focus:ring-offset-2",
+  {
+    variants: {
+      variant: {
+        default:
+          "border-transparent bg-primary text-primary-foreground hover:bg-primary/80",
+        secondary:
+          "border-transparent bg-secondary text-secondary-foreground hover:bg-secondary/80",
+        destructive:
+          "border-transparent bg-destructive text-destructive-foreground hover:bg-destructive/80",
+        outline: "text-foreground",
+      },
+    },
+    defaultVariants: {
+      variant: "default",
+    },
+  }
+)

frontend/src/components/ui/badge.tsx

@@ -1,26 +1,7 @@
 import * as React from "react"
-import { cva, type VariantProps } from "class-variance-authority"
+import type { VariantProps } from "class-variance-authority"
 import { cn } from "@/lib/utils"
-
-const badgeVariants = cva(
-  "inline-flex items-center rounded-full border px-2.5 py-0.5 text-xs font-semibold transition-colors focus:outline-none focus:ring-2 focus:ring-ring focus:ring-offset-2",
-  {
-    variants: {
-      variant: {
-        default:
-          "border-transparent bg-primary text-primary-foreground hover:bg-primary/80",
-        secondary:
-          "border-transparent bg-secondary text-secondary-foreground hover:bg-secondary/80",
-        destructive:
-          "border-transparent bg-destructive text-destructive-foreground hover:bg-destructive/80",
-        outline: "text-foreground",
-      },
-    },
-    defaultVariants: {
-      variant: "default",
-    },
-  }
-)
+import { badgeVariants } from "./badge-variants"
 
 export interface BadgeProps
   extends React.HTMLAttributes<HTMLDivElement>,
@@ -32,4 +13,4 @@ function Badge({ className, variant, ...props }: BadgeProps) {
   )
 }
 
-export { Badge, badgeVariants }
+export { Badge }

frontend/src/components/ui/button-variants.ts

@@ -0,0 +1,30 @@
+import { cva } from "class-variance-authority"
+
+export const buttonVariants = cva(
+  "inline-flex items-center justify-center whitespace-nowrap rounded-md text-sm font-medium ring-offset-background transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:pointer-events-none disabled:opacity-50",
+  {
+    variants: {
+      variant: {
+        default: "bg-primary text-primary-foreground hover:bg-primary/90",
+        destructive:
+          "bg-destructive text-destructive-foreground hover:bg-destructive/90",
+        outline:
+          "border border-input bg-background hover:bg-accent hover:text-accent-foreground",
+        secondary:
+          "bg-secondary text-secondary-foreground hover:bg-secondary/80",
+        ghost: "hover:bg-accent hover:text-accent-foreground",
+        link: "text-primary underline-offset-4 hover:underline",
+      },
+      size: {
+        default: "h-10 px-4 py-2",
+        sm: "h-9 rounded-md px-3",
+        lg: "h-11 rounded-md px-8",
+        icon: "h-10 w-10",
+      },
+    },
+    defaultVariants: {
+      variant: "default",
+      size: "default",
+    },
+  }
+)

frontend/src/components/ui/button.tsx

@@ -1,35 +1,7 @@
 import * as React from "react"
-import { cva, type VariantProps } from "class-variance-authority"
+import type { VariantProps } from "class-variance-authority"
 import { cn } from "@/lib/utils"
-
-const buttonVariants = cva(
-  "inline-flex items-center justify-center whitespace-nowrap rounded-md text-sm font-medium ring-offset-background transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:pointer-events-none disabled:opacity-50",
-  {
-    variants: {
-      variant: {
-        default: "bg-primary text-primary-foreground hover:bg-primary/90",
-        destructive:
-          "bg-destructive text-destructive-foreground hover:bg-destructive/90",
-        outline:
-          "border border-input bg-background hover:bg-accent hover:text-accent-foreground",
-        secondary:
-          "bg-secondary text-secondary-foreground hover:bg-secondary/80",
-        ghost: "hover:bg-accent hover:text-accent-foreground",
-        link: "text-primary underline-offset-4 hover:underline",
-      },
-      size: {
-        default: "h-10 px-4 py-2",
-        sm: "h-9 rounded-md px-3",
-        lg: "h-11 rounded-md px-8",
-        icon: "h-10 w-10",
-      },
-    },
-    defaultVariants: {
-      variant: "default",
-      size: "default",
-    },
-  }
-)
+import { buttonVariants } from "./button-variants"
 
 export interface ButtonProps
   extends React.ButtonHTMLAttributes<HTMLButtonElement>,
@@ -48,4 +20,4 @@ const Button = React.forwardRef<HTMLButtonElement, ButtonProps>(
 )
 Button.displayName = "Button"
 
-export { Button, buttonVariants }
+export { Button }

frontend/src/components/ui/dropdown-menu.tsx

@@ -11,7 +11,10 @@ const DropdownMenu = React.forwardRef<
     <div ref={ref} {...props}>
       {React.Children.map(children, (child) =>
         React.isValidElement(child)
-          ? React.cloneElement(child as React.ReactElement<any>, {
+          ? React.cloneElement(child as React.ReactElement<{
+          open?: boolean;
+          setOpen?: (open: boolean) => void;
+        }>, {
               open,
               setOpen,
             })

frontend/src/components/ui/theme-toggle.tsx

@@ -1,5 +1,5 @@
 import { Moon, Sun, Monitor } from 'lucide-react';
-import { useTheme } from '@/providers/ThemeProvider';
+import { useTheme } from '@/hooks/useTheme';
 import { Button } from '@/components/ui/button';
 import {
   DropdownMenu,

frontend/src/components/ui/toast-utils.ts

@@ -0,0 +1,14 @@
+interface Toast {
+  id: string
+  title?: string
+  description?: string
+  variant?: 'default' | 'destructive'
+}
+
+// Toast helper function - exported separately to avoid fast refresh issues
+export function showToast(props: Omit<Toast, 'id'>) {
+  window.dispatchEvent(new CustomEvent('toast', { detail: props }))
+}
+
+// Re-export Toast type for consumers
+export type { Toast };

frontend/src/components/ui/toaster.tsx

@@ -1,44 +1,40 @@
 import { useState, useEffect } from 'react'
+import type { Toast } from './toast-utils'
 
-interface Toast {
-  id: string
-  title?: string
-  description?: string
-  variant?: 'default' | 'destructive'
-}
+type ToastEvent = CustomEvent<Toast>
 
 const Toaster = () => {
   const [toasts, setToasts] = useState<Toast[]>([])
 
   useEffect(() => {
-    const handleToast = (e: CustomEvent<Toast>) => {
-      const toast = { ...e.detail, id: Math.random().toString(36) }
-      setToasts((prev) => [...prev, toast])
+    const handleToast = (e: ToastEvent) => {
+      const toastItem = { ...e.detail, id: Math.random().toString(36) }
+      setToasts((prev) => [...prev, toastItem])
       
       setTimeout(() => {
-        setToasts((prev) => prev.filter((t) => t.id !== toast.id))
+        setToasts((prev) => prev.filter((t) => t.id !== toastItem.id))
       }, 5000)
     }
 
-    window.addEventListener('toast' as any, handleToast)
-    return () => window.removeEventListener('toast' as any, handleToast)
+    window.addEventListener('toast', handleToast as EventListener)
+    return () => window.removeEventListener('toast', handleToast as EventListener)
   }, [])
 
   if (toasts.length === 0) return null
 
   return (
     <div className="fixed bottom-4 right-4 z-50 flex flex-col gap-2">
-      {toasts.map((toast) => (
+      {toasts.map((toastItem) => (
         <div
-          key={toast.id}
+          key={toastItem.id}
           className={`rounded-lg border p-4 shadow-lg ${
-            toast.variant === 'destructive'
+            toastItem.variant === 'destructive'
               ? 'border-destructive bg-destructive text-destructive-foreground'
               : 'border-border bg-background'
           }`}
         >
-          {toast.title && <div className="font-semibold">{toast.title}</div>}
-          {toast.description && <div className="text-sm">{toast.description}</div>}
+          {toastItem.title && <div className="font-semibold">{toastItem.title}</div>}
+          {toastItem.description && <div className="text-sm">{toastItem.description}</div>}
         </div>
       ))}
     </div>
@@ -46,6 +42,3 @@ const Toaster = () => {
 }
 
 export { Toaster }
-export const toast = (props: Omit<Toast, 'id'>) => {
-  window.dispatchEvent(new CustomEvent('toast', { detail: props }))
-}