Sentry improvements: context, tracing, source maps, privacy manifest

- Set Sentry user context (id, username) in Journal root for all routes
- Tag Planner errors with session_id
- Use reactRouterV7BrowserTracingIntegration for route-aware traces
- Hidden source maps (no sourceMappingURL in bundles, .map deleted after
  upload to Sentry)
- Privacy manifest at /privacy documenting all data collection
- robots.txt blocking all bots on both apps
- Suppress i18next promotional console log

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

openspec/changes/sentry-improvements/tasks.md

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+## 1. User & Session Context
+
+- [x] 1.1 Set Sentry user context (id, username) in Journal root loader/component when authenticated, clear when not
+- [x] 1.2 Set Sentry `session_id` tag in Planner's SessionView on mount
+
+## 2. Route-Aware Tracing
+
+- [x] 2.1 Replace `browserTracingIntegration()` with `reactRouterV7BrowserTracingIntegration` in planner entry.client.tsx
+- [x] 2.2 Replace `browserTracingIntegration()` with `reactRouterV7BrowserTracingIntegration` in journal entry.client.tsx
+
+## 3. Source Map Hardening
+
+- [x] 3.1 Change `build.sourcemap` from `true` to `"hidden"` in both vite.config.ts files
+- [x] 3.2 Add `sourcemaps.filesToDeleteAfterUpload` to the Sentry Vite plugin config to clean up .map files after upload
+
+## 4. Privacy Manifest
+
+- [x] 4.1 Create `/privacy` route in Journal with a user-visible privacy manifest documenting: what Sentry collects (errors, traces, session replays), what the Planner does NOT collect, data retention, and third-party disclosure (Sentry)
+- [x] 4.2 Add link to privacy manifest in Journal footer/home page
+
+## 5. Verify
+
+- [x] 5.1 Test locally: build, check no `.map` files remain in build output (or no sourceMappingURL in bundles)
+- [x] 5.2 Test locally: trigger error in Journal while logged in, verify Sentry.setUser was called (check devtools)