Implement daemon RPC with per-request context routing (bd-115)

- Added per-request storage routing in daemon server
  - Server now supports Cwd field in requests for database discovery
  - Tree-walking to find .beads/*.db from any working directory
  - Storage caching for performance across requests

- Created Python daemon client (bd_daemon_client.py)
  - RPC over Unix socket communication
  - Implements full BdClientBase interface
  - Auto-discovery of daemon socket from working directory

- Refactored bd_client.py with abstract interface
  - BdClientBase abstract class for common interface
  - BdCliClient for CLI-based operations (renamed from BdClient)
  - create_bd_client() factory with daemon/CLI fallback
  - Backwards-compatible BdClient alias

Next: Update MCP server to use daemon client when available

integrations/beads-mcp/tests/test_mcp_server_integration.py

@@ -70,16 +70,27 @@ async def mcp_client(bd_executable, temp_db, monkeypatch):
 
     # Reset client before test
     tools._client = None
+    
+    # Reset context environment variables
+    os.environ.pop("BEADS_CONTEXT_SET", None)
+    os.environ.pop("BEADS_WORKING_DIR", None)
+    os.environ.pop("BEADS_DB", None)
 
     # Create a pre-configured client with explicit paths (bypasses config loading)
-    tools._client = BdClient(bd_path=bd_executable, beads_db=temp_db)
+    temp_dir = os.path.dirname(temp_db)
+    tools._client = BdClient(bd_path=bd_executable, beads_db=temp_db, working_dir=temp_dir)
 
     # Create test client
     async with Client(mcp) as client:
+        # Automatically set context for the tests
+        await client.call_tool("set_context", {"workspace_root": temp_dir})
         yield client
 
-    # Reset client after test
+    # Reset client and context after test
     tools._client = None
+    os.environ.pop("BEADS_CONTEXT_SET", None)
+    os.environ.pop("BEADS_WORKING_DIR", None)
+    os.environ.pop("BEADS_DB", None)
 
 
 @pytest.mark.asyncio