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/superpowers/.pi-map.index.md

@@ -0,0 +1,23 @@
+# docs/superpowers (index)
+dir: docs/superpowers
+
+## role
+Documentation directory for special capabilities or advanced features of the project.
+## parent
+index: docs/.pi-map.index.md
+map: docs/.pi-map.md
+## children
+- docs/superpowers/plans
+  index: docs/superpowers/plans/.pi-map.index.md
+  map: docs/superpowers/plans/.pi-map.md
+- docs/superpowers/specs
+  index: docs/superpowers/specs/.pi-map.index.md
+  map: docs/superpowers/specs/.pi-map.md
+## files
+## links
+index: docs/superpowers/.pi-map.index.md
+map: docs/superpowers/.pi-map.md
+## workflows
+-
+## dirty
+-