ci: fix duplicate CI runs by limiting push triggers to main branch

Updated GitHub Actions workflow to:
- Only run on pushes to main branch
- Run on all pull requests to main branch

This prevents duplicate CI runs when pushing feature branches that
already have pull requests open, following GitHub Actions best practices.

Before:
- Push to feature branch: CI runs
- Open PR from feature branch: CI runs again (duplicate)

After:
- Push to feature branch: No CI run
- Open PR from feature branch: CI runs once
- Push to main: CI runs

Co-authored-by: f0ssel <[email protected]>

Author: blink-so[bot]

.github/workflows/ci.yml

@@ -2,7 +2,9 @@ name: CI
 
 on:
   push:
+    branches: [ main ]
   pull_request:
+    branches: [ main ]
 
 jobs:
   test: