fix(tui): Container change detection for proper differential rendering

Fixed rendering artifact where duplicate bottom borders appeared when components
dynamically shifted positions (e.g., Ctrl+C in agent clearing status container).

Root cause: Container wasn't reporting as "changed" when cleared (0 children),
causing differential renderer to skip re-rendering that area.

Solution: Container now tracks previousChildCount and reports changed when
child count changes, ensuring proper re-rendering when containers are cleared.

- Added comprehensive test reproducing the layout shift artifact
- Fixed Container to track and report child count changes
- All tests pass including new layout shift artifact test

packages/pods/src/models.json

@@ -231,13 +231,7 @@
 				{
 					"gpuCount": 1,
 					"gpuTypes": ["H200"],
-					"args": [
-						"--tool-call-parser",
-						"glm45",
-						"--reasoning-parser",
-						"glm45",
-						"--enable-auto-tool-choice"
-					],
+					"args": ["--tool-call-parser", "glm45", "--reasoning-parser", "glm45", "--enable-auto-tool-choice"],
 					"env": {
 						"VLLM_ATTENTION_BACKEND": "XFORMERS"
 					},