fix(types): resolve pyright errors introduced in #269 changes

- manifest.py: remove unused load_bottle_chain_from_dir import
- manifest_extends.py: drop redundant ManifestEgressRoute annotation
- test_cli_start_selector.py: remove unused call import
- test_cli_tui.py: move Optional/constants to top, annotate FakeScreen,
  remove unused curses import
- test_manifest_bottle_merge.py: add type args to dict, annotate **kwargs

tests/unit/test_manifest_bottle_merge.py

@@ -17,11 +17,11 @@ from bot_bottle.manifest import ManifestBottle, ManifestError, ManifestIndex
 from bot_bottle.manifest_extends import merge_bottles_runtime
 
 
-def _index(bottles: dict, agents: dict) -> ManifestIndex:
+def _index(bottles: dict[str, object], agents: dict[str, object]) -> ManifestIndex:
     return ManifestIndex.from_json_obj({"bottles": bottles, "agents": agents})
 
 
-def _bottle(**kwargs) -> ManifestBottle:
+def _bottle(**kwargs: object) -> ManifestBottle:
     return ManifestBottle.from_dict("test", kwargs)