refactor(text): extract shared summarization service with tts/note/notification modes

Move server-side summarization out of lib/tts/summarization.js into a shared
lib/text module exposing tts, note and notification modes. TTS and notification
runtimes now delegate to the shared service, note mode is used to distill a
selected excerpt into a short project note. Expose the new endpoint via
/api/text/summarize and route it through the common request middleware.

Client voice/summarize.ts accepts a mode option and points at the new
endpoint with an absolute URL that respects the desktop server origin.
VS Code webview swaps the stubbed tts summarize path for /api/text/summarize
and hardens URL parsing with window.location.href as the base.

packages/web/server/lib/opencode/core-routes.js

@@ -260,6 +260,7 @@ export const registerCommonRequestMiddleware = (app, dependencies) => {
       req.path.startsWith('/api/terminal') ||
       req.path.startsWith('/api/opencode') ||
       req.path.startsWith('/api/push') ||
+      req.path.startsWith('/api/text') ||
       req.path.startsWith('/api/voice') ||
       req.path.startsWith('/api/tts') ||
       req.path.startsWith('/api/openchamber/tunnel')