fix(backend): migrate TemplateResponse to starlette 1.x API

Starlette 1.x changed TemplateResponse signature from:
  TemplateResponse(name, {'request': request, ...})
to:
  TemplateResponse(request, name, {...})

Pass 'request' as first positional arg and remove it from context dict.
3 call sites fixed:
- backend/routers/auth.py (2 sites)
- backend/routers/integrations.py (1 site)

Failure-Class: none

Author: undivisible

backend/routers/auth.py

@@ -411,9 +411,9 @@ async def auth_callback_google(
     # The original ``redirect_uri`` was validated by ``_validate_redirect_uri`` at
     # ``/authorize`` time and cannot be overridden by the caller here.
     return templates.TemplateResponse(
+        request,
         "auth_callback.html",
         {
-            "request": request,
             "code": auth_code,
             "state": session_data['state'] or '',
             "redirect_uri": app_redirect_uri,
@@ -512,9 +512,9 @@ async def auth_callback_apple_post(
     # The original ``redirect_uri`` was validated by ``_validate_redirect_uri`` at
     # ``/authorize`` time and cannot be overridden by the caller here.
     return templates.TemplateResponse(
+        request,
         "auth_callback.html",
         {
-            "request": request,
             "code": auth_code,
             "state": session_data['state'] or '',
             "redirect_uri": app_redirect_uri,

backend/routers/integrations.py

@@ -93,7 +93,6 @@ def render_oauth_response(
 
     if success:
         context: Dict[str, Any] = {
-            'request': request,
             'title': f"{config['name']} Auth",
             'icon': '✓',
             'message': 'Authentication Successful!',
@@ -110,7 +109,6 @@ def render_oauth_response(
         }
 
         context = {
-            'request': request,
             'title': f"{config['name']} Auth Error",
             'icon': '❌',
             'message': f"{'Security' if error_type == 'invalid_state' else 'Configuration' if error_type == 'config_error' else 'Authentication'} Error",
@@ -119,7 +117,7 @@ def render_oauth_response(
             'show_spinner': False,
         }
 
-    return templates.TemplateResponse('oauth_callback.html', context)
+    return templates.TemplateResponse(request, 'oauth_callback.html', context)
 
 
 def validate_and_consume_oauth_state(state_token: Optional[str]) -> Optional[Dict[str, str]]: