feat: add web UI with login, CRUD, admin, and API key management

- Add login page with JWT authentication
- Add dashboard with stats and quick actions
- Add links management page (full CRUD with search)
- Add collections management page
- Add API key management page with copy-to-clipboard
- Add admin user management page (admin only)
- Fix UUID type mismatches across all endpoints
- Add updated_at column to api_keys and audit_log in schema.sql
- Fix DB_PASSWORD default in docker-compose.yml
- Add PyJWT to requirements.txt
- Fix API docs URL (/docs instead of /api/docs)
- Improve JS error handling (show actual messages)
- Rewrite conftest.py with proper DB lifecycle management
- Add 42 new integration tests (84 total, all passing)
  - test_admin.py: 15 tests for admin endpoints
  - test_auth_extended.py: 9 tests for API key CRUD
  - test_tags.py: 12 tests for tag endpoints
  - test_sync.py: 6 tests for sync endpoints

LinkSyncServer/static/js/main.js

@@ -15,7 +15,20 @@ document.addEventListener("DOMContentLoaded", function () {
             headers,
         });
         if (!response.ok) {
-            throw new Error(`API error: ${response.status}`);
+            let errorMsg = `HTTP ${response.status}`;
+            try {
+                const error = await response.json();
+                if (typeof error.detail === 'string') {
+                    errorMsg = error.detail;
+                } else if (Array.isArray(error.detail)) {
+                    errorMsg = error.detail.map(d => d.msg || d).join(', ');
+                } else if (error.detail && typeof error.detail === 'object') {
+                    errorMsg = error.detail.detail || error.detail.msg || JSON.stringify(error.detail);
+                }
+            } catch {
+                // ignore parse error, use default
+            }
+            throw new Error(errorMsg);
         }
         return response.json();
     }
@@ -50,6 +63,15 @@ document.addEventListener("DOMContentLoaded", function () {
                 body: JSON.stringify(data),
             });
         },
+        async updateCollection(id, data) {
+            return apiFetch(`/collections/${id}`, {
+                method: "PUT",
+                body: JSON.stringify(data),
+            });
+        },
+        async deleteCollection(id) {
+            return apiFetch(`/collections/${id}`, { method: "DELETE" });
+        },
         async executeQuery(expression, limit = 20) {
             return apiFetch(`/queries/execute?expression=${encodeURIComponent(expression)}&limit=${limit}`);
         },
@@ -67,8 +89,41 @@ document.addEventListener("DOMContentLoaded", function () {
             localStorage.setItem("token", data.access_token);
             return data;
         },
+        async getMe() {
+            return apiFetch("/auth/me");
+        },
         logout() {
             localStorage.removeItem("token");
+            localStorage.removeItem("user");
+        },
+        async getUsers() {
+            return apiFetch("/admin/users");
+        },
+        async createUser(data) {
+            return apiFetch("/admin/users", {
+                method: "POST",
+                body: JSON.stringify(data),
+            });
+        },
+        async updateUser(id, data) {
+            return apiFetch(`/admin/users/${id}`, {
+                method: "PUT",
+                body: JSON.stringify(data),
+            });
+        },
+        async deleteUser(id) {
+            return apiFetch(`/admin/users/${id}`, { method: "DELETE" });
+        },
+        async getApiKeys() {
+            return apiFetch("/auth/api-keys");
+        },
+        async createApiKey(name) {
+            return apiFetch(`/auth/api-key?name=${encodeURIComponent(name)}`, {
+                method: "POST",
+            });
+        },
+        async deleteApiKey(id) {
+            return apiFetch(`/auth/api-key/${id}`, { method: "DELETE" });
         },
     };
 });