## Why

SSH keys are required for git operations with external providers. Currently the SSHKey model exists but there's no API or UI to generate, manage, or use SSH keys.

## What Changes

- Add backend API endpoints for SSH key CRUD operations
- Implement Ed25519 key generation with Fernet encryption for private keys
- Add frontend page for SSH key management
- Display public keys with copy functionality

## Capabilities

### New Capabilities
- `ssh-key-management`: Generate and manage SSH keys for git operations

### Modified Capabilities
- None

## Impact

- `apps/api/src/api/`: New ssh_keys.py router
- `apps/api/src/models/ssh_key.py`: May need updates
- `apps/web/src/`: New SSH keys page
- `apps/api/src/main.py`: Register new router
