fix: Add .helmignore to exclude packages directory from helm lint

- helm lint was failing because pack files in .git/ and packages/*.tgz
  exceeded the 5MB file size limit
- Add .helmignore to exclude packages/, .git/, .gitea/ and *.tgz files

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

.helmignore

@@ -0,0 +1,22 @@
+# Patterns to ignore when building packages.
+# This supports shell glob matching, relative path matching, and
+# negation (prefixed with !). Only one pattern per line.
+.DS_Store
+# Common VCS dirs
+.git/
+.gitignore
+.gitea/
+# Common backup files
+*.swp
+*.bak
+*.tmp
+*.orig
+*~
+# Various IDEs
+.project
+.idea/
+*.tmproj
+.vscode/
+# Helm packages directory (pre-built packages)
+packages/
+*.tgz