feat: eager vLLM warmup and smart page titles in paginate stage

- Add warmup() to LlmProvider interface for eager subprocess startup
- ManagedVllmProvider.warmup() starts vLLM in background on project load
- ProviderRegistry.warmupAll() triggers all managed providers
- NamedProvider proxies warmup() to inner provider
- paginate stage generates LLM-powered descriptive page titles when
  available, cached by content hash, falls back to generic "Page N"
- project-mcp-endpoint calls warmupAll() on router creation so vLLM
  is loading while the session initializes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vitest.config.ts

@@ -9,6 +9,8 @@ export default defineConfig({
       exclude: ['**/node_modules/**', '**/dist/**', '**/*.config.*'],
     },
     include: ['src/*/tests/**/*.test.ts', 'tests/**/*.test.ts'],
+    exclude: ['**/node_modules/**', '**/smoke/**'],
     testTimeout: 10000,
+    globalSetup: ['src/db/tests/global-setup.ts'],
   },
 });