ci: Only trigger workflow on Java source file changes

Modified workflow to filter triggers by file paths:
- Runs on **.java file changes
- Runs when workflow itself is modified
- Still supports manual workflow_dispatch

This prevents unnecessary CI runs on documentation/config changes.

Author: claude

.github/workflows/release.yml

@@ -4,7 +4,13 @@ on:
   push:
     branches:
       - main
+    paths:
+      - '**.java'
+      - '.github/workflows/release.yml'
   pull_request:
+    paths:
+      - '**.java'
+      - '.github/workflows/release.yml'
   workflow_dispatch:
     inputs:
       version: