ci: add workflow_dispatch to mcp-mysql workflow

Path-filtered workflows don't fire on initial push — allows manual trigger.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: kpiwko

.github/workflows/mcp-mysql.yaml

@@ -1,6 +1,7 @@
 name: mcp-mysql
 
 on:
+  workflow_dispatch:
   push:
     branches: [main]
     paths: