feat(CF-1356): Add Sentry error tracking

Add sentry.ts with initSentry + withSentryTransaction, wrap all
tool call handlers with transaction tracing and error capture.

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

package.json

@@ -12,6 +12,7 @@
   },
   "dependencies": {
     "@modelcontextprotocol/sdk": "^1.0.4",
+    "@sentry/node": "^10.39.0",
     "dotenv": "^17.2.3"
   },
   "devDependencies": {