## Why

The platform now has authentication, data models, and a frontend foundation, but users still cannot manage projects end-to-end. Implementing project management is the next core workflow needed to organize repositories and execute real work.

## What Changes

- Implement authenticated project CRUD APIs with ownership enforcement.
- Add project listing views and project create/update/delete flows in the frontend.
- Add default SSH key selection per project and validate key ownership.
- Enforce cascading behavior for project deletion with related repositories and SSH key links.
- Add backend and frontend tests that cover auth, ownership, and error cases.

## Capabilities

### New Capabilities
- `project-management-ui`: Frontend project list/detail/form flows integrated with authenticated API.

### Modified Capabilities
- `project-management`: Expand requirement details for ownership checks, API contracts, and frontend-integrated project workflows.
- `git-repo`: Clarify cascade/delete behavior when repositories are removed through project deletion.
- `ssh-keys`: Clarify constraints for default project SSH key assignment.

## Impact

- Backend changes in `apps/api/src` (routes/services/models validation) and API tests.
- Frontend changes in `apps/web/src` (project pages, API client calls, forms, state handling).
- Potential migration adjustments if additional indexes/constraints are required for ownership/default-key integrity.
