Corregge delete path MediaMTX: usa HTTP DELETE.

Il POST restituiva 404 silenzioso e lasciava path alwaysAvailable attivi dopo fine diretta.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/mediamtx/client.rb

@@ -40,8 +40,13 @@ module Mediamtx
     end
 
     def delete_path_name(path_name)
-      @conn.post("/v3/config/paths/delete/#{CGI.escape(path_name)}")
+      response = @conn.delete("/v3/config/paths/delete/#{CGI.escape(path_name)}")
+      unless response.success?
+        err = response.body.is_a?(Hash) ? response.body["error"] : response.body
+        raise Error, "MediaMTX path delete failed: #{response.status} #{err}"
+      end
       forget_always_available(path_name)
+      true
     end
 
     def set_path_recording(session, enabled:)