fix: Resolve admin dashboard route conflict causing 500 error

CRITICAL production hotfix for v1.1.1-rc.2 addressing route conflict
that caused 500 errors on /admin/dashboard.

Changes:
- Renamed metrics dashboard route from /admin/dashboard to /admin/metrics-dashboard
- Added defensive imports for missing monitoring module with graceful fallback
- Updated version to 1.1.1-rc.2
- Updated CHANGELOG with hotfix details
- Created implementation report in docs/reports/

Testing:
- All 32 admin route tests pass (100%)
- 593/600 total tests pass (7 pre-existing failures unrelated to hotfix)
- Verified backward compatibility maintained

Design:
- Follows ADR-022 architecture decision
- Implements design from docs/design/hotfix-v1.1.1-rc2-route-conflict.md
- No breaking changes - all existing url_for() calls work correctly

Production Impact:
- Resolves 500 error at /admin/dashboard
- Notes dashboard remains at /admin/ (unchanged)
- Metrics dashboard now at /admin/metrics-dashboard
- Graceful degradation when monitoring module unavailable

Generated with [Claude Code](https://claude.com/claude-code)

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

CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.1.1-rc.2] - 2025-11-25
+
+### Fixed
+- **CRITICAL**: Resolved route conflict causing 500 error on /admin/dashboard
+  - Renamed metrics dashboard route from `/admin/dashboard` to `/admin/metrics-dashboard`
+  - Added defensive imports to handle missing monitoring module gracefully
+  - All existing `url_for("admin.dashboard")` calls continue to work correctly
+  - Notes dashboard at `/admin/` remains unchanged and functional
+  - See ADR-022 for design rationale
+
 ## [1.1.1] - 2025-11-25
 
 ### Added