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).

apps/.pi-map.md

@@ -0,0 +1,18 @@
+# apps
+dir: apps
+
+index: apps/.pi-map.index.md
+
+## role
+Contains the main application entry points and executable modules for the project.
+## files
+## arch
+Typically follows a modular architecture where each subdirectory represents a separate deployable application sharing common domain libraries.
+## tags
+-
+## symbols
+-
+## workflows
+-
+## dirty
+-