refactor(dashboard): change SpawnModal from overlay modal to dropdown

Position the spawn modal directly under the 'New Agent' button without a
blur overlay. Uses click-outside dismissal and absolute positioning.
Reduces visual disruption for quick agent spawning.

tests/test_zellij_metadata.py

@@ -13,7 +13,7 @@ import tempfile
 import types
 import unittest
 from pathlib import Path
-from unittest.mock import MagicMock, patch, call
+from unittest.mock import MagicMock, patch
 
 # ---------------------------------------------------------------------------
 # Import hook module (no .py extension)
@@ -24,8 +24,8 @@ amc_hook.__file__ = str(hook_path)
 code = compile(hook_path.read_text(), hook_path, "exec")
 exec(code, amc_hook.__dict__)  # noqa: S102 - loading local module
 
-# Import spawn mixin
-import amc_server.mixins.spawn as spawn_mod
+# Import spawn mixin (after hook loading - intentional)
+import amc_server.mixins.spawn as spawn_mod  # noqa: E402
 
 
 # ===========================================================================