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/archive/2026-05-17-project-management/.pi-map.md

@@ -1,10 +1,10 @@
-# openspec/changes/archive/2026-05-17-project-management
-dir: openspec/changes/archive/2026-05-17-project-management
+# archive/2026-05-17-project-management
+dir: archive/2026-05-17-project-management
 
-index: openspec/changes/archive/2026-05-17-project-management/.pi-map.index.md
+index: archive/2026-05-17-project-management/.pi-map.index.md
 
 ## role
-Archive directory containing historical specification documents for a full-stack project management feature with authentication, ownership, and SSH key integration.
+This package contains archived design documentation and planning artifacts for a project management feature that was implemented with full-stack CRUD operations, ownership enforcement, and SSH key integration.
 ## files
 - .openspec.yaml | Defines an OpenAPI specification file metadata with schema type and creation date
 - README.md | Defines a project management application that implements create, read, update, delete, listing, and ownership workflows across API and frontend layers
@@ -12,7 +12,7 @@ Archive directory containing historical specification documents for a full-stack
 - proposal.md | Proposes a project management feature implementation covering authenticated CRUD APIs, frontend flows, SSH key integration, and cascading deletion behavior. | dep: authentication, data models, frontend foundation, apps/api/src, apps/web/src
 - tasks.md | Tracks completed tasks for implementing full-stack project management features with ownership enforcement and verification checks.
 ## arch
-Specification-driven development using OpenAPI metadata, phased design documents (proposal → design → tasks → README), and cross-layer (API/frontend) CRUD workflow planning with ownership-based access control.
+Documentation-driven planning architecture using OpenAPI specification metadata, structured markdown design documents (proposal → design → tasks → README), and explicit separation of API/backend concerns from frontend integration workflows.
 ## tags
 project, frontend, management, ownership, design, tasks, defines, .openspec
 ## symbols