Reorganize to dedicated namespaces with automatic cleanup

**Namespace Structure:**
- neonvortex: Application deployment and webhook listener
- flux-builds: Build jobs with automatic cleanup
- flux-system: Flux CD control plane (unchanged)

**Automatic Cleanup:**
- Build jobs: 30-minute TTL after completion
- Cleanup CronJob: Runs every 30 minutes
  - Keeps last 10 successful builds
  - Deletes failed jobs older than 1 hour
  - Removes all jobs older than 24 hours

**Changes:**
- Moved HelmRelease from default to neonvortex namespace
- Moved build jobs from default to flux-builds namespace
- Updated webhook listener to create jobs in flux-builds
- Updated Flux alerts to monitor new namespace
- Cleaned up all resources from default namespace
- Added dedicated ServiceAccounts and RBAC per namespace

**Benefits:**
- Clean namespace separation for better organization
- Automatic job cleanup prevents resource accumulation
- Build history maintained (last 10 successful builds)
- Improved monitoring and troubleshooting
- Default namespace is now clean

Comprehensive migration guide in NAMESPACE_MIGRATION_GUIDE.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

flux-alerts-neonvortex.yaml

@@ -0,0 +1,35 @@
+---
+apiVersion: notification.toolkit.fluxcd.io/v1beta3
+kind: Alert
+metadata:
+  name: neon-vortex-git
+  namespace: flux-system
+spec:
+  summary: "Neon Vortex Git Updates"
+  providerRef:
+    name: neon-vortex-notify
+  eventSeverity: info
+  eventSources:
+    - kind: GitRepository
+      name: neon-vortex
+      namespace: flux-system
+  exclusionList:
+    - ".*health check.*"
+---
+apiVersion: notification.toolkit.fluxcd.io/v1beta3
+kind: Alert
+metadata:
+  name: neon-vortex-deploy
+  namespace: flux-system
+spec:
+  summary: "Neon Vortex Deployment Status"
+  providerRef:
+    name: neon-vortex-notify
+  eventSeverity: info
+  eventSources:
+    - kind: HelmRelease
+      name: neon-vortex
+      namespace: neonvortex
+  exclusionList:
+    - ".*health check.*"
+    - ".*reconciliation in progress.*"