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/.pi-map.index.md

@@ -0,0 +1,40 @@
+# openspec (index)
+dir: openspec
+
+## role
+Defines and configures a living documentation methodology and project governance rules for AI-assisted software development.
+## parent
+index: ./.pi-map.index.md
+map: ./.pi-map.md
+## children
+- openspec/changes
+  index: openspec/changes/.pi-map.index.md
+  map: openspec/changes/.pi-map.md
+- openspec/designs
+  index: openspec/designs/.pi-map.index.md
+  map: openspec/designs/.pi-map.md
+- openspec/docs
+  index: openspec/docs/.pi-map.index.md
+  map: openspec/docs/.pi-map.md
+- openspec/explorations
+  index: openspec/explorations/.pi-map.index.md
+  map: openspec/explorations/.pi-map.md
+- openspec/proposals
+  index: openspec/proposals/.pi-map.index.md
+  map: openspec/proposals/.pi-map.md
+- openspec/specs
+  index: openspec/specs/.pi-map.index.md
+  map: openspec/specs/.pi-map.md
+- openspec/tasks
+  index: openspec/tasks/.pi-map.index.md
+  map: openspec/tasks/.pi-map.md
+## files
+- README.md
+- config.yaml
+## links
+index: openspec/.pi-map.index.md
+map: openspec/.pi-map.md
+## workflows
+-
+## dirty
+-