refactor: store workspaces as {workspace_id}/{repo_name} for natural git clone layout

Working copies were stored as /data/working-copies/{repo_id}/{workspace_name}/,
so git clone was forced into a user-named directory. That meant the container
mount basename was the workspace name (e.g. main) instead of the repo name.

- Generate the workspace UUID before cloning and clone into
  /data/working-copies/{workspace_id}/ so git creates {repo_name}/ naturally
- Set workspace.path to /data/working-copies/{workspace_id}/{repo_name}/
- Update _migrate_clone_into_workspace() to use the same layout
- _get_repository_mount_name() now prefers workspace.path basename and only
  falls back to remote URL / repo.name for legacy repo-only instances
- Update unit tests to assert workspace path basename is used for mounts

Quality gates:
- pytest tests/unit: 219 passed
- ruff: clean on changed files
- mypy: clean on changed files

apps/.pi-map.md

@@ -4,10 +4,10 @@ dir: apps
 index: apps/.pi-map.index.md
 
 ## role
-Contains the main application entry points and executable modules for the project.
+Contains the main executable applications and entry points for the project
 ## files
 ## arch
-Typically follows a modular architecture where each subdirectory represents a separate deployable application or service, often with shared libraries extracted to common packages.
+Modular application architecture with separate deployable units, likely following a microservices or service-oriented pattern where each subdirectory represents an independent application with its own configuration, dependencies, and lifecycle
 ## tags
 -
 ## symbols