fix: sync all version files to 0.30.2 and add CI check

The 0.30.2 bump was done manually and missed several files:
- .claude-plugin/plugin.json (was 0.30.0)
- .claude-plugin/marketplace.json (was 0.30.0)
- npm-package/package.json (was 0.30.1)
- integrations/beads-mcp/pyproject.toml (was 0.30.1)
- integrations/beads-mcp/src/beads_mcp/__init__.py (was 0.30.1)

Added scripts/check-versions.sh and CI job to prevent this in future.
Always use scripts/bump-version.sh for version bumps.

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

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

npm-package/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@beads/bd",
-  "version": "0.30.1",
+  "version": "0.30.2",
   "description": "Beads issue tracker - lightweight memory system for coding agents with native binary support",
   "main": "bin/bd.js",
   "bin": {