Add modular app structure for L2 server

- Create app factory with routers and templates
- Auth, assets, activities, anchors, storage, users, renderers routers
- Federation router for WebFinger and nodeinfo
- Jinja2 templates for L2 pages
- Config and dependency injection

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/dependencies.py

@@ -0,0 +1,80 @@
+"""
+L2 Server Dependency Injection.
+
+Provides common dependencies for routes.
+"""
+
+from typing import Optional
+
+from fastapi import Request, HTTPException, Depends
+from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
+
+from .config import settings
+
+security = HTTPBearer(auto_error=False)
+
+
+def get_templates(request: Request):
+    """Get Jinja2 templates from app state."""
+    return request.app.state.templates
+
+
+async def get_current_user(request: Request) -> Optional[dict]:
+    """
+    Get current user from cookie or header.
+
+    Returns user dict or None if not authenticated.
+    """
+    from auth import verify_token, get_token_claims
+
+    # Try cookie first
+    token = request.cookies.get("auth_token")
+
+    # Try Authorization header
+    if not token:
+        auth_header = request.headers.get("Authorization", "")
+        if auth_header.startswith("Bearer "):
+            token = auth_header[7:]
+
+    if not token:
+        return None
+
+    # Verify token
+    username = verify_token(token)
+    if not username:
+        return None
+
+    # Get full claims
+    claims = get_token_claims(token)
+    if not claims:
+        return None
+
+    return {
+        "username": username,
+        "actor_id": f"https://{settings.domain}/users/{username}",
+        "token": token,
+        **claims,
+    }
+
+
+async def require_auth(request: Request) -> dict:
+    """
+    Require authentication.
+
+    Raises HTTPException 401 if not authenticated.
+    """
+    user = await get_current_user(request)
+    if not user:
+        raise HTTPException(401, "Authentication required")
+    return user
+
+
+def get_user_from_cookie(request: Request) -> Optional[str]:
+    """Get username from cookie (for HTML pages)."""
+    from auth import verify_token
+
+    token = request.cookies.get("auth_token")
+    if not token:
+        return None
+
+    return verify_token(token)