fix(deploy): Checkpoints — preserve STOPPED history, fix filter + placement

- Backend: rename deleteTerminalByAppAndEnvironment → deleteFailedByAppAndEnvironment.
  STOPPED rows were being wiped on every redeploy, so Checkpoints was always empty.
  Now only FAILED rows are pruned; STOPPED deployments are retained as restorable
  checkpoints (they still carry deployed_config_snapshot from their RUNNING window).
- UI filter: any deployment with a snapshot is a checkpoint (was RUNNING|DEGRADED only,
  which excluded the main case — the previous blue/green deployment now in STOPPED).
- UI placement: Checkpoints disclosure now renders inside IdentitySection, matching
  the design spec.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cameleer-server-app/src/main/java/com/cameleer/server/app/storage/PostgresDeploymentRepository.java

@@ -126,8 +126,8 @@ public class PostgresDeploymentRepository implements DeploymentRepository {
     }
 
     @Override
-    public void deleteTerminalByAppAndEnvironment(UUID appId, UUID environmentId) {
-        jdbc.update("DELETE FROM deployments WHERE app_id = ? AND environment_id = ? AND status IN ('STOPPED', 'FAILED')",
+    public void deleteFailedByAppAndEnvironment(UUID appId, UUID environmentId) {
+        jdbc.update("DELETE FROM deployments WHERE app_id = ? AND environment_id = ? AND status = 'FAILED'",
                 appId, environmentId);
     }