Add MCP tools for migration inspection (bd-627d Phase 3)

- Add inspect_migration() tool - calls bd migrate --inspect --json
- Add get_schema_info() tool - calls bd info --schema --json
- Implements abstract methods in BdClientBase
- CLI client calls commands directly
- Daemon client raises NotImplementedError (rare admin commands)

Phase 3 complete. Agents can now inspect migrations via MCP before running them.

Amp-Thread-ID: https://ampcode.com/threads/T-de7e1141-87ac-4b4a-9cea-1b7bc4d51da9
Co-authored-by: Amp <amp@ampcode.com>

integrations/beads-mcp/src/beads_mcp/bd_daemon_client.py

@@ -430,6 +430,28 @@ class BdDaemonClient(BdClientBase):
         # This is a placeholder for when it's added
         raise NotImplementedError("Blocked operation not yet supported via daemon")
 
+    async def inspect_migration(self) -> dict:
+        """Get migration plan and database state for agent analysis.
+
+        Returns:
+            Migration plan dict with registered_migrations, warnings, etc.
+
+        Note:
+            This falls back to CLI since migrations are rare operations
+        """
+        raise NotImplementedError("inspect_migration not supported via daemon - use CLI client")
+
+    async def get_schema_info(self) -> dict:
+        """Get current database schema for inspection.
+
+        Returns:
+            Schema info dict with tables, version, config, sample IDs, etc.
+
+        Note:
+            This falls back to CLI since schema inspection is a rare operation
+        """
+        raise NotImplementedError("get_schema_info not supported via daemon - use CLI client")
+
     async def add_dependency(self, params: AddDependencyParams) -> None:
         """Add a dependency between issues.