chore(e2e): implement Phase 6 integration testing with agent skills

Complete Phase 6 of Playwright E2E testing plan with comprehensive
integration tests covering cross-feature workflows and system integration.

Integration Tests Added:

proxy-acl-integration.spec.ts - ACL with proxy host integration
proxy-certificate.spec.ts - SSL certificate lifecycle tests
proxy-dns-integration.spec.ts - DNS challenge provider integration
security-suite-integration.spec.ts - Cerberus security suite tests
backup-restore-e2e.spec.ts - Full backup/restore workflow
import-to-production.spec.ts - Caddyfile/CrowdSec import flows
multi-feature-workflows.spec.ts - Complex multi-step scenarios
Agent Skills Created:

docker-rebuild-e2e.SKILL.md - Rebuild E2E Docker environment
test-e2e-playwright-debug.SKILL.md - Run/debug Playwright tests
Supporting scripts for skill execution
Test Infrastructure Improvements:

TestDataManager for namespace-based test isolation
Fixed route paths: /backups → /tasks/backups
Domain uniqueness via UUID namespacing
Improved selector reliability with role-based queries
Results: 648 tests passing, 98 skipped, 97.5% statement coverage

.vscode/tasks.json

@@ -440,6 +440,54 @@
                 "panel": "dedicated",
                 "close": false
             }
+        },
+        {
+            "label": "Docker: Rebuild E2E Environment",
+            "type": "shell",
+            "command": ".github/skills/scripts/skill-runner.sh docker-rebuild-e2e",
+            "group": "build",
+            "problemMatcher": [],
+            "presentation": {
+                "reveal": "always",
+                "panel": "dedicated",
+                "close": false
+            }
+        },
+        {
+            "label": "Docker: Rebuild E2E Environment (Clean)",
+            "type": "shell",
+            "command": ".github/skills/scripts/skill-runner.sh docker-rebuild-e2e --clean --no-cache",
+            "group": "build",
+            "problemMatcher": [],
+            "presentation": {
+                "reveal": "always",
+                "panel": "dedicated",
+                "close": false
+            }
+        },
+        {
+            "label": "Test: E2E Playwright (Debug Mode)",
+            "type": "shell",
+            "command": ".github/skills/scripts/skill-runner.sh test-e2e-playwright-debug",
+            "group": "test",
+            "problemMatcher": [],
+            "presentation": {
+                "reveal": "always",
+                "panel": "dedicated",
+                "close": false
+            }
+        },
+        {
+            "label": "Test: E2E Playwright (Debug with Inspector)",
+            "type": "shell",
+            "command": ".github/skills/scripts/skill-runner.sh test-e2e-playwright-debug --inspector",
+            "group": "test",
+            "problemMatcher": [],
+            "presentation": {
+                "reveal": "always",
+                "panel": "dedicated",
+                "close": false
+            }
         }
     ],
     "inputs": [