chore: archive 15 completed OpenSpec changes

Move the following audited-and-implemented changes into
openspec/changes/archive/2026-06-12-completed-changes-archive/:

- backend-frontend-refactoring
- config-profile-git-mounts
- config-profile-includes-ui
- config-profile-multi-repo-mounts
- container-monitoring-notifications
- git-mount-url-validation
- home-path-expansion
- mobile-terminal-ux
- mount-specificity-ordering
- notification-center
- persistent-terminal-sessions
- session-list-overhaul
- ssh-key-mounting
- terminal-fullscreen-unified-header
- tool-session-progress-and-updates

Also regenerated .pi-map*.md files for openspec/changes so the
remaining active changes (multi-session-terminal-ux, reorganize-long-files,
working-copies, workspace-first-ui) reflect the new layout.

openspec/changes/.pi-map.md

@@ -1,13 +1,27 @@
-# openspec/changes
-dir: openspec/changes
+# .
+dir: .
 
-index: openspec/changes/.pi-map.index.md
+index: ./.pi-map.index.md
+
+## Project Map Protocol
+
+1. Read this protocol and the root `.pi-map.index.md` first.
+2. Use `index:` / `map:` references to open relevant directory indexes and maps.
+3. Load indexes before rich maps during task-start navigation.
+4. Read the local rich map and actual source before editing.
+5. Treat non-empty `## dirty` sections in either artifact as stale.
+6. If source and generated artifacts disagree, trust source.
+7. If map and index disagree, trust neither blindly; verify from source and regenerate the pair.
+8. After editing source, run `project_map_patch` for each changed file.
+9. Before broad architectural claims or final handoff, run `project_map_validate` when freshness matters.
+
+Trust boundary: index routes, map orients, source decides.
 
 ## role
-Implements a version control and change tracking system for managing schema evolution and data migrations in the OpenSpec framework.
+Empty root directory awaiting package initialization or content.
 ## files
 ## arch
-Event-sourced architecture with command pattern for immutable change records, supporting branching/merging semantics and incremental schema transformations.
+N/A - no files or architectural patterns present to analyze.
 ## tags
 -
 ## symbols