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

Makefile

@@ -1,6 +1,12 @@
 # Makefile for nvm-auto-use.fish
 
-.PHONY: help install-tools lint lint-fish lint-markdown lint-json lint-fix lint-check test clean
+# URLs and constants
+FISHER_BASE := https://raw.githubusercontent.com/jorgebucaran/fisher/main
+FISHER_URL := $(FISHER_BASE)/functions/fisher.fish
+
+.PHONY: help install-tools lint lint-fish lint-markdown lint-json \
+	lint-fix lint-check lint-editorconfig test test-ci test-unit \
+	test-integration clean
 
 # Default target
 help:
@@ -12,28 +18,28 @@ help:
 	@echo "  lint-json       - Lint JSON files"
 	@echo "  lint-fix        - Fix auto-fixable linting issues"
 	@echo "  lint-check      - Check linting without fixing"
+	@echo "  lint-editorconfig - Check EditorConfig compliance"
 	@echo "  test            - Run tests (install plugin locally)"
 	@echo "  test-ci         - Run tests in CI environment"
+	@echo "  test-unit       - Run unit tests only"
+	@echo "  test-integration - Run integration tests only"
 	@echo "  clean           - Clean temporary files"
 
 # Install all required linting tools
 install-tools:
 	@echo "Installing linting tools..."
-	# Install markdownlint-cli for markdown linting
 	@if ! command -v markdownlint >/dev/null 2>&1; then \
 		echo "Installing markdownlint-cli..."; \
 		npm install -g markdownlint-cli; \
 	else \
 		echo "markdownlint-cli already installed"; \
 	fi
-	# Install jsonlint for JSON linting
 	@if ! command -v jsonlint >/dev/null 2>&1; then \
 		echo "Installing jsonlint..."; \
 		npm install -g jsonlint; \
 	else \
 		echo "jsonlint already installed"; \
 	fi
-	# Install jq for JSON processing (backup)
 	@if ! command -v jq >/dev/null 2>&1; then \
 		echo "Installing jq..."; \
 		if command -v brew >/dev/null 2>&1; then \
@@ -51,18 +57,19 @@ install-tools:
 	@echo "All linting tools installed!"
 
 # Run all linting checks
-lint: lint-fish lint-markdown lint-json
+lint: lint-fish lint-markdown lint-json lint-editorconfig
 
 # Lint Fish shell files
 lint-fish:
 	@echo "Linting Fish files..."
-	@find . -name "*.fish" -type f | while read -r file; do \
-		echo "Checking $$file..."; \
-		fish_indent --check "$$file" || { \
-			echo "Formatting issues found in $$file"; \
-			exit 1; \
-		}; \
-	done
+	@find . \
+		-name "*.fish" \
+		-type f \
+		-exec sh -c \
+		'echo "Checking $$1..."; \
+		fish_indent --check "$$1" || { \
+			echo "Formatting issues found in $$1"; exit 1; }' \
+		sh {} \;
 	@echo "Validating Fish syntax..."
 	@fish -n functions/*.fish completions/*.fish 2>/dev/null || { \
 		echo "Syntax errors found in Fish files"; \
@@ -86,24 +93,36 @@ lint-markdown:
 # Lint JSON files
 lint-json:
 	@echo "Linting JSON files..."
-	@find . -name "*.json" -type f | while read -r file; do \
-		echo "Checking $$file..."; \
+	@find . \
+		-name "*.json" \
+		-type f \
+		-exec sh -c \
+		'file="$$1"; echo "Checking $$file..."; \
 		if command -v jsonlint >/dev/null 2>&1; then \
 			jsonlint "$$file" >/dev/null || { \
-				echo "JSON syntax error in $$file"; \
-				exit 1; \
-			}; \
+				echo "JSON syntax error in $$file"; exit 1; }; \
 		elif command -v jq >/dev/null 2>&1; then \
 			jq empty "$$file" >/dev/null || { \
-				echo "JSON syntax error in $$file"; \
-				exit 1; \
-			}; \
+				echo "JSON syntax error in $$file"; exit 1; }; \
 		else \
-			echo "No JSON linter found, skipping $$file"; \
-		fi; \
-	done
+			echo "No JSON linter found, skipping $$file"; fi' \
+		sh {} \;
 	@echo "JSON files passed linting!"
 
+# Check EditorConfig compliance
+lint-editorconfig:
+	@echo "Checking EditorConfig compliance..."
+	@if command -v editorconfig-checker >/dev/null 2>&1; then \
+		editorconfig-checker; \
+	elif command -v ec >/dev/null 2>&1; then \
+		ec; \
+	else \
+		echo "Installing editorconfig-checker..."; \
+		.github/install_editorconfig-checker.sh; \
+		editorconfig-checker; \
+	fi
+	@echo "EditorConfig compliance passed!"
+
 # Fix auto-fixable linting issues
 lint-fix:
 	@echo "Fixing linting issues..."
@@ -134,7 +153,7 @@ test:
 test-ci:
 	@echo "Testing plugin installation in CI..."
 	@fish -c "\
-		curl -sL https://raw.githubusercontent.com/jorgebucaran/fisher/main/functions/fisher.fish | source; \
+		curl -sL $(FISHER_URL) | source; \
 		fisher install jorgebucaran/fisher; \
 		if fisher list | string match -q '*ivuorinen/nvm-auto-use.fish*'; \
 			echo 'Plugin already installed, skipping installation'; \
@@ -143,9 +162,30 @@ test-ci:
 		end; \
 		echo 'Plugin test completed successfully in CI!'"
 
+# Run unit tests
+test-unit:
+	@echo "Running unit tests..."
+	@chmod +x tests/test_runner.fish
+	@for test in tests/unit/*.fish; do \
+		echo "Running $$test..."; \
+		fish "$$test" || exit 1; \
+	done
+	@echo "Unit tests completed!"
+
+# Run integration tests
+test-integration:
+	@echo "Running integration tests..."
+	@chmod +x tests/test_runner.fish
+	@for test in tests/integration/*.fish; do \
+		echo "Running $$test..."; \
+		fish "$$test" || exit 1; \
+	done
+	@echo "Integration tests completed!"
+
 # Clean temporary files
 clean:
 	@echo "Cleaning temporary files..."
 	@find . -name "*.tmp" -type f -delete 2>/dev/null || true
 	@find . -name ".DS_Store" -type f -delete 2>/dev/null || true
-	@echo "Cleanup complete!"
+	@nvm_cache clear 2>/dev/null || true
+	@echo "Cleanup complete!"