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).

docs/architecture/.pi-map.index.md

@@ -0,0 +1,24 @@
+# docs/architecture (index)
+dir: docs/architecture
+
+## role
+Documents the technical architecture and system design for the "Headquarter" full-stack application across all layers.
+## parent
+index: docs/.pi-map.index.md
+map: docs/.pi-map.md
+## children
+- docs/architecture/decisions
+  index: docs/architecture/decisions/.pi-map.index.md
+  map: docs/architecture/decisions/.pi-map.md
+## files
+- backend.md
+- database.md
+- deployment.md
+- frontend.md
+## links
+index: docs/architecture/.pi-map.index.md
+map: docs/architecture/.pi-map.md
+## workflows
+-
+## dirty
+-