Delete push notification token
Delete a registered push notification token.
**Features:**
- Remove device token from all collections
- Clean up topic subscriptions
- User ownership verification
- Complete token removal
**Authentication:**
- Requires valid Bearer token
- Users can only delete their own tokens
- Test tokens available for development: `test-jwt-token`, `agent-jwt-token`
**Use Cases:**
- User logout and token cleanup
- Device uninstallation
- Security token revocation
- Privacy compliance (GDPR)
**Token Cleanup:**
- Removes from user's token list
- Removes from platform-specific collections
- Removes from device-specific collections
- Unsubscribes from all topics
- Cleans up Redis cache
**Example Request:**
```
DELETE /notifications/tokens/token_123
Authorization: Bearer your-jwt-token
```
