chore: track all project map and index files

Add generated .pi-map.md and .pi-map.index.md files across the repository
so the project navigation maps are shared and versioned. These artifacts
are maintained by project_map_init/patch/validate and must be kept in
sync with source edits.

Note: .cache/ remains ignored (added in previous commit).

openspec/specs/sessions-hub/.pi-map.index.md

@@ -0,0 +1,19 @@
+# openspec/specs/sessions-hub (index)
+dir: openspec/specs/sessions-hub
+
+## role
+Defines technical specifications for a centralized user session management feature that enables viewing, filtering, and terminating active sessions across devices.
+## parent
+index: openspec/specs/.pi-map.index.md
+map: openspec/specs/.pi-map.md
+## children
+-
+## files
+- spec.md
+## links
+index: openspec/specs/sessions-hub/.pi-map.index.md
+map: openspec/specs/sessions-hub/.pi-map.md
+## workflows
+-
+## dirty
+-

openspec/specs/sessions-hub/.pi-map.md

@@ -0,0 +1,19 @@
+# openspec/specs/sessions-hub
+dir: openspec/specs/sessions-hub
+
+index: openspec/specs/sessions-hub/.pi-map.index.md
+
+## role
+Defines technical specifications for a centralized user session management feature that enables viewing, filtering, and terminating active sessions across devices.
+## files
+- spec.md | Defines technical specifications for a "Sessions Hub" feature including requirements, API endpoints, UI layouts, state management, and quality gates for managing user sessions in a web application. | dep: REST API, TypeScript, React/frontend framework (implied by UI specs and quality gates), polling-based state management, Pydantic/BaseModel
+## arch
+Specification-driven design using structured documentation with hierarchical sections (requirements, API, UI, state, quality gates) to enforce contract-first development between frontend and backend teams.
+## tags
+sessions, spec, defines, technical, specifications, hub, feature, including
+## symbols
+-
+## workflows
+-
+## dirty
+-