feat(tool-configs): add frontend tool config management page

- Create ToolConfigsPage with tool type selector, config list, and add/edit form
- Support both env and file config types
- Add route /tool-configs and navigation item
- Update API client with tool config endpoints
- Build passes successfully

apps/web/src/api/tool_configs.ts

@@ -0,0 +1,56 @@
+import { apiClient } from "./client";
+
+export interface ToolConfig {
+  id: string;
+  tool_type_id: string;
+  project_id: string | null;
+  key: string;
+  value: string;
+  config_type: string;
+  file_path: string | null;
+}
+
+export interface CreateToolConfigRequest {
+  tool_type_id: string;
+  project_id?: string;
+  key: string;
+  value: string;
+  config_type?: string;
+  file_path?: string;
+}
+
+export const listToolConfigs = async (
+  tool_type_id?: string,
+  project_id?: string
+): Promise<ToolConfig[]> => {
+  const params = new URLSearchParams();
+  if (tool_type_id) params.append("tool_type_id", tool_type_id);
+  if (project_id) params.append("project_id", project_id);
+  
+  const response = await apiClient.get<{ configs: ToolConfig[] }>(
+    `/tool-configs?${params.toString()}`
+  );
+  return response.data.configs;
+};
+
+export const createToolConfig = async (
+  data: CreateToolConfigRequest
+): Promise<ToolConfig> => {
+  const response = await apiClient.post<{ configs: ToolConfig[] }>("/tool-configs", data);
+  return response.data.configs[0];
+};
+
+export const updateToolConfig = async (
+  id: string,
+  data: CreateToolConfigRequest
+): Promise<ToolConfig> => {
+  const response = await apiClient.put<{ configs: ToolConfig[] }>(
+    `/tool-configs/${id}`,
+    data
+  );
+  return response.data.configs[0];
+};
+
+export const deleteToolConfig = async (id: string): Promise<void> => {
+  await apiClient.delete(`/tool-configs/${id}`);
+};