Update repomix install check and expand doc testing API

Changed Makefile to check for repomix using 'command -v' instead of 'npm list -g'. Expanded and corrected the documentation_testing.json API definitions, adding new controller methods, fixing parameter type formatting, and improving descriptions for clarity and completeness.

Author: karangattu

Makefile

@@ -125,7 +125,7 @@ docs-quartodoc: FORCE
 
 install-repomix: install-npm ## Install repomix if not already installed
 	@echo "-------- Installing repomix if needed --------"
-	@if ! npm list -g repomix > /dev/null 2>&1; then \
+	@if ! command -v repomix > /dev/null 2>&1; then \
 		echo "Installing repomix..."; \
 		npm install -g repomix; \
 	else \