refactor: move Helm chart to standard directory structure

This commit restructures the paperless-ai Helm chart by moving all files
 from the nested directory (charts/paperless-ai/paperless-ai/) to the
 standard Helm chart directory structure (charts/paperless-ai/). The change
 eliminates the redundant directory nesting that was causing issues with
 Helm chart packaging and installation. No functional changes were made to
 any files - this is purely a directory structure reorganization to follow
 Helm best practices and improve chart maintainability.

charts/paperless-ai/.helmignore

@@ -0,0 +1,23 @@
+# 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
+.bzr/
+.bzrignore
+.hg/
+.hgignore
+.svn/
+# Common backup files
+*.swp
+*.bak
+*.tmp
+*.orig
+*~
+# Various IDEs
+.project
+.idea/
+*.tmproj
+.vscode/