feat: refactor plugin architecture, enhance linting, CI & tooling

- Major refactor of core Fish functions for modularity, caching, and error handling
- Improved `.editorconfig` and Makefile for stricter formatting and linting standards
- Expanded linting support: added EditorConfig checks, auto-install for missing tools, and Makefile targets
- Enhanced CI workflow with clearer permissions and job steps in GitHub Actions
- Updated documentation in `README.md` and `CLAUDE.md` to reflect new features, advanced developer tools, and contribution guidelines
- Improved Node.js version manager detection, switching, and installation logic
- Added/updated utility functions for configuration, silent mode, notifications, and version extraction
- Various bug fixes, code quality improvements, and expanded test coverage

functions/nvm_version_prompt.fish

@@ -9,10 +9,13 @@ end
 
 function nvm_version_status -d "Show detailed Node.js version status"
     if command -q node
-        set -l version (node -v 2>/dev/null)
-        set -l npm_version (npm -v 2>/dev/null)
+        set -l version (node -v 2>/dev/null | string replace -r '^v' '')
+        set -l npm_version
+        if command -q npm
+            set npm_version (npm -v 2>/dev/null)
+        end
 
-        echo "Node.js: $version"
+        echo "Node.js: v$version"
         if test -n "$npm_version"
             echo "npm: v$npm_version"
         end