fix: phase 0 quick wins — safety, naming, and portability

- Add helm.sh/resource-policy: keep to PVC (prevent data loss on uninstall)
- Add fail guard for empty name value in Helm templates
- Fix Makefile IMAGE_NAME from antigravity to devcontainer
- Pin busybox:1.37, homeassistant:v6.7.1, playwright:v0.0.68 (was latest/stable)
- Set imagePullPolicy: IfNotPresent on pinned sidecars
- Remove fetch/sequentialthinking from .mcp.json (sidecars removed from chart)
- Default storage.className to empty (use cluster default, was ceph-filesystem)
- Default Happy Coder URLs to empty (was private farh.net endpoints)
- Broaden githubRepo schema to accept GitLab/Gitea URLs
- Add unknown IDE warning before VSCode fallback
- Add mkdir -p before credential file write (fix fresh PVC boot)
- Guard app user existence in cont-init-user.sh
- Add NOTES.txt post-install template with port-forward and secret hints
- Add standard app.kubernetes.io/* labels and separate selectorLabels

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/init-repo.sh

@@ -22,6 +22,7 @@ if [ -n "$GITHUB_TOKEN" ]; then
 
     # Create or update the credentials file
     CREDENTIALS_FILE="/config/userdata/.git-credentials"
+    mkdir -p "$(dirname "$CREDENTIALS_FILE")"
 
     # Support multiple git hosting providers
     # GitHub supports both oauth2 and token as username
@@ -51,6 +52,7 @@ else
 
     # Create an empty credentials file with proper permissions
     CREDENTIALS_FILE="/config/userdata/.git-credentials"
+    mkdir -p "$(dirname "$CREDENTIALS_FILE")"
     touch "$CREDENTIALS_FILE"
     chmod 600 "$CREDENTIALS_FILE"