feat(websearch): add multi-tier MCP fallback for third-party profiles

Implements CCS WebSearch Native Infrastructure (Phases 1-3):

Phase 1 - Multi-tier MCP Fallback:
- Add mcp-manager.ts with ensureMcpWebSearch() for auto-configuration
- Support web-search-prime (primary), Brave Search, and Tavily MCPs
- Case-insensitive detection of existing web search MCPs
- Block-websearch hook for optional native WebSearch blocking

Phase 2 - User Configuration:
- Add WebSearchConfig interface to unified-config-types.ts
- Add getWebSearchConfig() to unified-config-loader.ts
- Support configurable webSearchPrimeUrl for security
- Add GET/PUT /api/websearch endpoints in routes.ts
- Add WebSearch settings UI in settings.tsx dashboard

Phase 3 - Documentation & Testing:
- Add WebSearch section to README.md
- Create comprehensive docs/websearch.md guide
- Add 23 unit tests for MCP manager logic

Enables web search for gemini, codex, agy, qwen, glm, kimi profiles
that cannot access Anthropic's native WebSearch API.

src/ccs.ts

@@ -14,6 +14,7 @@ import { detectClaudeCli } from './utils/claude-detector';
 import { getSettingsPath } from './utils/config-manager';
 import { ErrorManager } from './utils/error-manager';
 import { execClaudeWithCLIProxy, CLIProxyProvider } from './cliproxy';
+import { ensureMcpWebSearch } from './utils/mcp-manager';
 
 // Import extracted command handlers
 import { handleVersionCommand } from './commands/version-command';
@@ -378,6 +379,10 @@ async function main(): Promise<void> {
       const customSettingsPath = profileInfo.settingsPath; // undefined for hardcoded profiles
       await execClaudeWithCLIProxy(claudeCli, provider, remainingArgs, { customSettingsPath });
     } else if (profileInfo.type === 'settings') {
+      // Settings-based profiles (glm, glmt, kimi) are third-party providers
+      // WebSearch is server-side tool - third-party providers have no access
+      ensureMcpWebSearch();
+
       // Check if this is GLMT profile (requires proxy)
       if (profileInfo.name === 'glmt') {
         // GLMT FLOW: Settings-based with embedded proxy for thinking support