chore: archive observability-service-registry, track pi-map artifacts

- Archive the completed observability-service-registry SDD change into
  openspec/changes/archive/ (delivered across 5 slices; only
  jellyfin-service-registry remains active).
- Stop ignoring .pi-map.md / .pi-map.index.md so the navigation maps are
  versioned alongside the code, and add the regenerated map pairs repo-wide.

frontend/src/components/__tests__/.pi-map.index.md

@@ -0,0 +1,32 @@
+# frontend/src/components/__tests__ (index)
+dir: frontend/src/components/__tests__
+
+## role
+Test suite providing unit test coverage for reusable UI components and feature widgets in the frontend.
+## parent
+index: frontend/src/components/.pi-map.index.md
+map: frontend/src/components/.pi-map.md
+## children
+-
+## files
+- BackupAlertsTable.test.tsx
+- BackupDashboardWidget.test.tsx
+- BackupRunsTable.test.tsx
+- ConfirmDialog.test.tsx
+- DialogFooter.test.tsx
+- HoverEditButton.test.tsx
+- LibraryOverview.test.tsx
+- MetricCard.test.tsx
+- NowPlaying.test.tsx
+- SectionCard.test.tsx
+- SelectionRailCard.test.tsx
+- SessionActivityPanel.test.tsx
+- TabbedCard.test.tsx
+## links
+index: frontend/src/components/__tests__/.pi-map.index.md
+map: frontend/src/components/__tests__/.pi-map.md
+## workflows
+- update __tests__ tests
+  read: BackupAlertsTable.test.tsx, BackupDashboardWidget.test.tsx, BackupRunsTable.test.tsx
+## dirty
+-

frontend/src/components/__tests__/.pi-map.md

@@ -0,0 +1,32 @@
+# frontend/src/components/__tests__
+dir: frontend/src/components/__tests__
+
+index: frontend/src/components/__tests__/.pi-map.index.md
+
+## role
+Test suite providing unit test coverage for reusable UI components and feature widgets in the frontend.
+## files
+- BackupAlertsTable.test.tsx | Unit tests for the BackupAlertsTable component verifying severity badge mapping, acknowledge button behavior, and conditional rendering | dep: vitest, @testing-library/react, @testing-library/user-event, ../BackupAlertsTable, ../../types/backups, BackupAlertsTable component, BackupAlert type
+- BackupDashboardWidget.test.tsx | Unit tests for BackupDashboardWidget component covering loading, success, and alert states | dep: vitest, @testing-library/react, ../BackupDashboardWidget, ../../hooks/useBackups, BackupDashboardWidget, useBackupDashboard hook
+- BackupRunsTable.test.tsx | Tests the BackupRunsTable component's status-to-badge variant mapping and formatting of duration/bytes values. | dep: vitest, @testing-library/react, ../BackupRunsTable, ../../types/backups, BackupRunsTable, types/backups
+- ConfirmDialog.test.tsx | Tests the ConfirmDialog component's rendering behavior and user interaction handlers. | dep: vitest, @testing-library/react, @testing-library/user-event, ../ConfirmDialog, ConfirmDialog
+- DialogFooter.test.tsx | Tests the DialogFooter component's rendering, callback wiring, busy state, destructive styling, and secondary action support. | dep: vitest, @testing-library/react, @testing-library/user-event, ../DialogFooter
+- HoverEditButton.test.tsx | Tests the HoverEditButton component's click behavior and label customization. | dep: vitest, @testing-library/react, @testing-library/user-event, ../HoverEditButton, HoverEditButton
+- LibraryOverview.test.tsx | Tests the LibraryOverview component renders movie and TV library cards with correct counts | dep: vitest, @testing-library/react, ../LibraryOverview, ../../types, LibraryOverview component, LibraryCount type
+- MetricCard.test.tsx | Tests the MetricCard component rendering with and without optional subtext prop | dep: vitest, @testing-library/react, ../MetricCard
+- NowPlaying.test.tsx | Tests the NowPlaying component's empty-state rendering when no sessions exist | dep: vitest, @testing-library/react, ../NowPlaying, NowPlaying component
+- SectionCard.test.tsx | Unit tests for the SectionCard component verifying it renders title, description, action, and children correctly | dep: vitest, @testing-library/react, ../SectionCard, SectionCard
+- SelectionRailCard.test.tsx | Unit tests for the SelectionRailCard component verifying it renders title, body, footer, and applies minHeight prop correctly. | dep: vitest, @testing-library/react, ../SelectionRailCard, SelectionRailCard
+- SessionActivityPanel.test.tsx | Tests the SessionActivityPanel component's rendering of session states, empty state, and user interaction callbacks. | dep: vitest, @testing-library/react, @testing-library/user-event, ../SessionActivityPanel, ../../types, SessionActivityPanel, types
+- TabbedCard.test.tsx | Tests the TabbedCard component's rendering and tab selection behavior | dep: vitest, @testing-library/react, @testing-library/user-event, ../TabbedCard, @/components/ui/tabs
+## arch
+Component-level React Testing Library tests organized as co-located per-component test files following a flat naming convention.
+## tags
+library, @testing, tests, component, vitest, react, user, card.test
+## symbols
+-
+## workflows
+- update __tests__ tests
+  read: BackupAlertsTable.test.tsx, BackupDashboardWidget.test.tsx, BackupRunsTable.test.tsx
+## dirty
+-