feat(ui): reconnect release investigation routes [SPRINT-022]

Mount deploy-diff, change-trace, and timeline under /releases/investigation
as bounded secondary routes. Timeline uses correlation-based model to avoid
collision with shipped run-workspace tab.

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

docs/features/checked/web/release-investigation-routes.md

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+# Release Investigation Routes Reconnection
+
+## Module
+Web
+
+## Status
+IMPLEMENTED
+
+## Sprint
+SPRINT_20260308_022_FE_unreachable_release_investigation_routes
+
+## Description
+Integrated disconnected release-investigation route families (timeline, deploy-diff, change-trace) into the canonical Releases product under a bounded `/releases/investigation/` prefix. The investigation timeline is mounted as a secondary route to avoid colliding with the shipped run workspace tab at `/releases/runs/:runId/timeline`.
+
+## Canonical URL Contract
+- `/releases/investigation/timeline` - Investigation timeline overview
+- `/releases/investigation/timeline/:correlationId` - Correlated event drill-in
+- `/releases/investigation/deploy-diff` - Deployment diff (query params: from, to)
+- `/releases/investigation/change-trace` - Change trace viewer
+- `/releases/investigation/change-trace/:traceId` - Specific trace detail
+
+## Timeline Decision
+**Bounded-secondary-route** (not absorb-into-run-workspace). The investigation timeline is a correlation-based tool that spans multiple services by correlationId, which is conceptually different from the run workspace's timeline tab showing run execution flow. Mounting it under `/releases/investigation/timeline` avoids URL collision and keeps both capabilities distinct.
+
+## Implementation Details
+- **Route file**: `src/Web/StellaOps.Web/src/app/routes/releases.routes.ts`
+  - Added three `loadChildren` entries under `investigation/` prefix
+- **Feature routes updated**:
+  - `src/Web/StellaOps.Web/src/app/features/timeline/timeline.routes.ts` - Added breadcrumb, title, sprint ref
+  - `src/Web/StellaOps.Web/src/app/features/deploy-diff/deploy-diff.routes.ts` - Updated canonical URL reference
+  - `src/Web/StellaOps.Web/src/app/features/change-trace/change-trace.routes.ts` - Added breadcrumb, title, sprint ref
+- **Tests**: `src/Web/StellaOps.Web/src/app/routes/releases.routes.spec.ts`
+
+## Deliberately Excluded Legacy Behaviors
+- The old timeline route at `/timeline` (standalone top-level) is not revived
+- Direct mounting at `/releases/runs/:runId/timeline` for the investigation timeline is explicitly avoided (that path is owned by the run workspace)