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>

.claude-plugin/marketplace.json

@@ -9,7 +9,7 @@
       "name": "beads",
       "source": "./",
       "description": "AI-supervised issue tracker for coding workflows",
-      "version": "0.30.3"
+      "version": "0.30.4"
     }
   ]
 }