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/templates/.pi-map.index.md

@@ -0,0 +1,21 @@
+# docs/templates (index)
+dir: docs/templates
+
+## role
+Provides standardized markdown templates for consistent documentation of APIs, architecture, and features across the project.
+## parent
+index: docs/.pi-map.index.md
+map: docs/.pi-map.md
+## children
+-
+## files
+- api-endpoint.md
+- architecture.md
+- feature-doc.md
+## links
+index: docs/templates/.pi-map.index.md
+map: docs/templates/.pi-map.md
+## workflows
+-
+## dirty
+-