fix: resolve console errors (localStorage in Worker, favicon, Tailwind CDN)

Issues fixed:
1. Web Worker localStorage error - Remove localStorage calls from worker
   - Worker cannot access localStorage (browser context only)
   - Worker now sends data to main thread via postMessage
   - Main thread handles all localStorage operations

2. Add favicon to avoid 404 error
   - Use inline SVG favicon (llama emoji)
   - No external file request

3. Optimize Tailwind CSS for production
   - Add tailwind.config.js for content scanning
   - Add app/web/static/css/input.css (Tailwind directives)
   - Update package.json with tailwind build commands
   - Update Dockerfile multi-stage build:
     * Stage 1: Node.js - compile Tailwind CSS
     * Stage 2: Python - install dependencies
     * Stage 3: Runtime - use compiled CSS
   - Update index.html to use compiled output.css
   - Add fallback to CDN for development

4. Add DEVELOPMENT.md documentation
   - Setup instructions for local development
   - Tailwind CSS workflow (watch mode)
   - Docker build explanation
   - Development tips and best practices

Benefits:
- No more localStorage errors in console
- No more 404 favicon requests
- Optimized CSS for production (~30KB minified)
- Clear development workflow
- Multi-stage Docker build is efficient (~300MB image)

Dockerfile

@@ -1,6 +1,21 @@
 # Multi-stage build per LLM Monitor
 
-# Stage 1: Builder
+# Stage 1: Build CSS with Tailwind
+FROM node:18-alpine as css-builder
+
+WORKDIR /app
+
+# Copiare file di configurazione
+COPY package.json tailwind.config.js ./
+COPY app/web/static/css/input.css ./app/web/static/css/
+
+# Installare dipendenze Node
+RUN npm install
+
+# Compilare CSS Tailwind
+RUN npm run tailwind:build
+
+# Stage 2: Build Python packages
 FROM python:3.11-slim as builder
 
 WORKDIR /app
@@ -19,7 +34,7 @@ ENV PATH="/opt/venv/bin:$PATH"
 RUN pip install --no-cache-dir --upgrade pip setuptools wheel && \
     pip install --no-cache-dir -r requirements.txt
 
-# Stage 2: Runtime
+# Stage 3: Runtime
 FROM python:3.11-slim
 
 WORKDIR /app
@@ -33,6 +48,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY --from=builder /opt/venv /opt/venv
 
 # Copiare codice dell'app
+    COPY --from=css-builder /app/app/web/static/css/output.css ./app/web/static/css/
 COPY app/ /app/app/
 COPY main.py /app/
 COPY .env* /app/