chore(release): bump version to 0.48.0

Release highlights:
- VersionedStorage interface for pluggable backends
- bd types command and enhancement type alias
- bd close -m flag (git commit convention)
- RepoContext API for centralized git operations
- Dolt backend improvements (WIP)
- Many bug fixes for doctor, sync, hooks, worktrees

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

.claude-plugin/marketplace.json

@@ -9,7 +9,7 @@
       "name": "beads",
       "source": "./claude-plugin",
       "description": "AI-supervised issue tracker for coding workflows",
-      "version": "0.47.2"
+      "version": "0.48.0"
     }
   ]
 }