chore: track .pi-map.md and .pi-map.index.md artifacts

Remove the map files from .gitignore so they are committed as project
navigation artifacts, and also unignore them in the sample fixture.
Regenerate all maps so the committed versions reflect the current source.

fixtures/sample-project/tests/.pi-map.index.md

@@ -0,0 +1,21 @@
+# fixtures/sample-project/tests (index)
+dir: fixtures/sample-project/tests
+
+## role
+Provides unit test coverage for user model behavior and string validation utilities in the sample project.
+## parent
+index: fixtures/sample-project/.pi-map.index.md
+map: fixtures/sample-project/.pi-map.md
+## children
+-
+## files
+- user.test.ts
+- validation.test.ts
+## links
+index: fixtures/sample-project/tests/.pi-map.index.md
+map: fixtures/sample-project/tests/.pi-map.md
+## workflows
+- update tests tests
+  read: user.test.ts, validation.test.ts
+## dirty
+-

fixtures/sample-project/tests/.pi-map.md

@@ -0,0 +1,21 @@
+# fixtures/sample-project/tests
+dir: fixtures/sample-project/tests
+
+index: fixtures/sample-project/tests/.pi-map.index.md
+
+## role
+Provides unit test coverage for user model behavior and string validation utilities in the sample project.
+## files
+- user.test.ts | Unit tests for user model creation, validation, and serialization | dep: vitest, ../src/models/user.js
+- validation.test.ts | Unit tests for string validation utility functions | dep: vitest, ../src/utils/validation.js
+## arch
+Standard test suite using isolated unit tests with file-based grouping by domain concern (model vs. utility).
+## tags
+validation, unit, tests, user, vitest, src, js, user.test
+## symbols
+-
+## workflows
+- update tests tests
+  read: user.test.ts, validation.test.ts
+## dirty
+-