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/changes/archive/2026-05-23-remove-built-in-tools/.pi-map.index.md

@@ -0,0 +1,24 @@
+# openspec/changes/archive/2026-05-23-remove-built-in-tools (index)
+dir: openspec/changes/archive/2026-05-23-remove-built-in-tools
+
+## role
+Contains planning and design documents for a refactoring initiative to remove the special-cased "built-in" tool type classification and migrate to a unified database-driven tool type system.
+## parent
+index: openspec/changes/archive/.pi-map.index.md
+map: openspec/changes/archive/.pi-map.md
+## children
+- openspec/changes/archive/2026-05-23-remove-built-in-tools/specs
+  index: openspec/changes/archive/2026-05-23-remove-built-in-tools/specs/.pi-map.index.md
+  map: openspec/changes/archive/2026-05-23-remove-built-in-tools/specs/.pi-map.md
+## files
+- .openspec.yaml
+- design.md
+- proposal.md
+- tasks.md
+## links
+index: openspec/changes/archive/2026-05-23-remove-built-in-tools/.pi-map.index.md
+map: openspec/changes/archive/2026-05-23-remove-built-in-tools/.pi-map.md
+## workflows
+-
+## dirty
+-