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/components/navbar.html

@@ -0,0 +1,21 @@
+<nav class="container-fluid">
+    <ul>
+        <li><strong><a href="/" class="navbar-brand">OpenRouter Monitor</a></strong></li>
+    </ul>
+    <ul>
+        {% if user %}
+        <li><a href="/dashboard">Dashboard</a></li>
+        <li><a href="/keys">API Keys</a></li>
+        <li><a href="/tokens">Tokens</a></li>
+        <li><a href="/profile">Profile</a></li>
+        <li>
+            <form action="/logout" method="POST" style="display: inline;" hx-post="/logout" hx-redirect="/login">
+                <button type="submit" class="outline">Logout</button>
+            </form>
+        </li>
+        {% else %}
+        <li><a href="/login">Login</a></li>
+        <li><a href="/register" role="button">Register</a></li>
+        {% endif %}
+    </ul>
+</nav>