feat: implement MCP provider registry and service

- Add provider registry to manage LLM providers (Claude, Codex, Cursor, Gemini).
- Create provider routes for MCP server operations (list, upsert, delete, run).
- Implement MCP service for handling server operations and validations.
- Introduce abstract provider class and MCP provider base for shared functionality.
- Add tests for MCP server operations across different providers and scopes.
- Define shared interfaces and types for MCP functionality.
- Implement utility functions for handling JSON config files and API responses.

server/modules/providers/provider.registry.ts

@@ -0,0 +1,36 @@
+import { ClaudeProvider } from '@/modules/providers/list/claude/claude.provider.js';
+import { CodexProvider } from '@/modules/providers/list/codex/codex.provider.js';
+import { CursorProvider } from '@/modules/providers/list/cursor/cursor.provider.js';
+import { GeminiProvider } from '@/modules/providers/list/gemini/gemini.provider.js';
+import type { IProvider } from '@/shared/interfaces.js';
+import type { LLMProvider } from '@/shared/types.js';
+import { AppError } from '@/shared/utils.js';
+
+const providers: Record<LLMProvider, IProvider> = {
+  claude: new ClaudeProvider(),
+  codex: new CodexProvider(),
+  cursor: new CursorProvider(),
+  gemini: new GeminiProvider(),
+};
+
+/**
+ * Central registry for resolving provider MCP implementations by id.
+ */
+export const providerRegistry = {
+  listProviders(): IProvider[] {
+    return Object.values(providers);
+  },
+
+  resolveProvider(provider: string): IProvider {
+    const key = provider as LLMProvider;
+    const resolvedProvider = providers[key];
+    if (!resolvedProvider) {
+      throw new AppError(`Unsupported provider "${provider}".`, {
+        code: 'UNSUPPORTED_PROVIDER',
+        statusCode: 400,
+      });
+    }
+
+    return resolvedProvider;
+  },
+};