fix(hooks): prevent post-merge hook failure on no dependency changes (#16)

## Summary
- Fix `grep` exit code 1 propagating as hook failure when no dependency
files changed
- Add `|| true` to suppress non-zero exit from `grep` with no matches

## Test plan
- [x] Merge a branch that doesn't change `package.json` or
`pnpm-lock.yaml` — no hook error
- [x] Merge a branch that changes dependencies — reminder message still
shown

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: marcstraube

.husky/post-merge

@@ -1,7 +1,7 @@
 #!/bin/sh
 
 # Check if package.json or pnpm-lock.yaml changed
-CHANGED=$(git diff-tree -r --name-only --no-commit-id ORIG_HEAD HEAD 2>/dev/null | grep -E '^(package\.json|pnpm-lock\.yaml)$')
+CHANGED=$(git diff-tree -r --name-only --no-commit-id ORIG_HEAD HEAD 2>/dev/null | grep -E '^(package\.json|pnpm-lock\.yaml)$' || true)
 
 if [ -n "$CHANGED" ]; then
   echo ""