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/src/models/.pi-map.md

@@ -0,0 +1,25 @@
+# apps/api/src/models
+dir: apps/api/src/models
+
+index: apps/api/src/models/.pi-map.index.md
+
+## role
+Provides the core database model layer with a centralized public API, defining SQLAlchemy base classes and reusable mixins for consistent schema patterns across the API application.
+## files
+- __init__.py | Re-exports model classes from submodules to provide a centralized public API for the src.models package | dep: src.models.base, src.models.config.config_profile, src.models.project.git_repository, src.models.project.project, src.models.project.workspace, src.models.system.health_check, src.models.system.instance_event, src.models.system.notification, src.models.system.terminal_session, src.models.tool.tool_definition_manifest, src.models.tool.tool_instance, src.models.tool.tool_type, src.models.user.ssh_key, src.models.user.user, src.models.user.user_config
+- base.py | Defines SQLAlchemy base model and reusable mixins for UUID primary keys and automatic timestamp tracking in database models. | exp: class:Base, class:UUIDPrimaryKeyMixin, class:TimestampMixin | dep: uuid, datetime, sqlalchemy, sqlalchemy.orm
+## arch
+Uses the declarative base pattern with mixin composition for cross-cutting concerns (UUIDs, timestamps), and a facade/aggregate module pattern via __init__.py re-exports to simplify imports for consumers.
+## tags
+models, src, base, project, system, user, mixin, tool
+## symbols
+- Base
+- UUIDPrimaryKeyMixin
+- TimestampMixin
+## workflows
+- change models behavior
+  read: __init__.py, base.py
+- explore models subdirectories
+  index: apps/api/src/models/config/.pi-map.index.md, apps/api/src/models/project/.pi-map.index.md, apps/api/src/models/system/.pi-map.index.md
+## dirty
+-