feat: restyle admin UI and add per-user sync run history

Adds a self-hosted stylesheet (no CDN dependencies) with a card-based
dashboard and color-coded status badges, and shows the last 10 sync
runs per user on the detail page.

app/web/routes.py

@@ -7,7 +7,7 @@ from fastapi.templating import Jinja2Templates
 from app.auth.admin import password_matches, require_admin
 from app.auth.csrf import ensure_csrf_token, validate_csrf
 from app.db.models import SyncUser
-from app.db.repositories import ActivityRepository, UserRepository
+from app.db.repositories import ActivityRepository, SyncRunRepository, UserRepository
 from app.security.credentials import CredentialCipher
 from app.web.forms import UserFormData
 
@@ -132,6 +132,7 @@ def user_detail(request: Request, user_id: int):
     with request.app.state.session_factory() as session:
         user = _get_user_or_404(UserRepository(session), user_id)
         activities = ActivityRepository(session).list_pending_for_user(user_id)
+        recent_runs = SyncRunRepository(session).list_recent_for_user(user_id, limit=10)
         return templates.TemplateResponse(
             request,
             "users/detail.html",
@@ -139,6 +140,7 @@ def user_detail(request: Request, user_id: int):
                 "csrf_token": ensure_csrf_token(request),
                 "user": user,
                 "activities": activities,
+                "recent_runs": recent_runs,
             },
         )