feat(frontend): T44 setup FastAPI static files and templates

- Mount static files on /static endpoint
- Configure Jinja2Templates with directory structure
- Create base template with Pico.css, HTMX, Chart.js
- Create all template subdirectories (auth, dashboard, keys, tokens, profile, components)
- Create initial CSS and JS files
- Add tests for static files and templates configuration

Tests: 12 passing
Coverage: 100% on new configuration code

templates/auth/login.html

@@ -0,0 +1,42 @@
+{% extends "base.html" %}
+
+{% block title %}Login - OpenRouter Monitor{% endblock %}
+
+{% block content %}
+<article class="grid">
+    <div>
+        <h1>Login</h1>
+        <p>Enter your credentials to access the dashboard.</p>
+    </div>
+    <div>
+        <form action="/login" method="POST" hx-post="/login" hx-swap="outerHTML" hx-target="this">
+            {% if error %}
+            <div class="alert alert-danger" role="alert">
+                {{ error }}
+            </div>
+            {% endif %}
+            
+            <label for="email">
+                Email
+                <input type="email" id="email" name="email" placeholder="your@email.com" required>
+            </label>
+            
+            <label for="password">
+                Password
+                <input type="password" id="password" name="password" placeholder="Password" required minlength="8">
+            </label>
+            
+            <fieldset>
+                <label for="remember">
+                    <input type="checkbox" id="remember" name="remember" role="switch">
+                    Remember me
+                </label>
+            </fieldset>
+            
+            <button type="submit">Login</button>
+        </form>
+        
+        <p>Don't have an account? <a href="/register">Register here</a>.</p>
+    </div>
+</article>
+{% endblock %}