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/api/tests/.pi-map.index.md

@@ -0,0 +1,36 @@
+# apps/api/tests (index)
+dir: apps/api/tests
+
+## role
+Shared testing infrastructure and fixtures for the FastAPI API application
+## parent
+index: apps/api/.pi-map.index.md
+map: apps/api/.pi-map.md
+## children
+- apps/api/tests/api
+  index: apps/api/tests/api/.pi-map.index.md
+  map: apps/api/tests/api/.pi-map.md
+- apps/api/tests/integration
+  index: apps/api/tests/integration/.pi-map.index.md
+  map: apps/api/tests/integration/.pi-map.md
+- apps/api/tests/services
+  index: apps/api/tests/services/.pi-map.index.md
+  map: apps/api/tests/services/.pi-map.md
+- apps/api/tests/system
+  index: apps/api/tests/system/.pi-map.index.md
+  map: apps/api/tests/system/.pi-map.md
+- apps/api/tests/unit
+  index: apps/api/tests/unit/.pi-map.index.md
+  map: apps/api/tests/unit/.pi-map.md
+## files
+- conftest.py
+## links
+index: apps/api/tests/.pi-map.index.md
+map: apps/api/tests/.pi-map.md
+## workflows
+- change tests behavior
+  read: conftest.py
+- explore tests subdirectories
+  index: apps/api/tests/api/.pi-map.index.md, apps/api/tests/integration/.pi-map.index.md, apps/api/tests/services/.pi-map.index.md
+## dirty
+-