chore: Bump version to 0.30.4

Updated all component versions:
- bd CLI: 0.30.3 → 0.30.4
- Plugin: 0.30.3 → 0.30.4
- MCP server: 0.30.3 → 0.30.4
- npm package: 0.30.3 → 0.30.4

New features:
- bd template instantiate for YAML workflow templates
- --assignee flag for template instantiation
- Fixed mail inbox --identity filtering
- Fixed orphan detection false positives

Note: Graph link edges (relates_to, replies_to, etc.) and mail commands
are experimental and subject to breaking changes.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/templates/hooks/post-merge

@@ -1,5 +1,5 @@
 #!/bin/sh
-# bd-hooks-version: 0.30.3
+# bd-hooks-version: 0.30.4
 #
 # bd (beads) post-merge hook
 #