refactor(cli): address nuanced snapshot rendering scenarios through layout and padding refinements

- Refined height calculation logic in ToolGroupMessage to ensure consistent spacing between compact and standard tools.
- Adjusted padding and margins in StickyHeader, ToolConfirmationQueue, ShellToolMessage, and ToolMessage for visual alignment.
- Updated TOOL_RESULT_STANDARD_RESERVED_LINE_COUNT to account for internal layout changes.
- Improved ToolResultDisplay height handling in alternate buffer mode.
- Updated test snapshots to reflect layout and spacing corrections.

refactor(cli): cleanup and simplify UI components

- Reduced UI refresh delay in AppContainer.tsx for a more responsive user experience.
- Reorder imports and hook definitions within AppContainer.tsx to reduce diff 'noise'.

refactor(cli): enhance compact output robustness and visual regression testing

Addressing automated review feedback to improve code maintainability and layout stability.

1. Robust File Extension Parsing:
- Introduced getFileExtension utility in packages/cli/src/ui/utils/fileUtils.ts using node:path for reliable extension extraction.
- Updated DenseToolMessage and DiffRenderer to use the new utility, replacing fragile string splitting.

2. Visual Regression Coverage:
- Added SVG snapshot tests to DenseToolMessage.test.tsx to verify semantic color rendering and layout integrity in compact mode.

fix(cli): resolve dense tool output code quality issues

- Replaced manual string truncation with Ink's `wrap="truncate-end"` to adhere to UI guidelines.
- Added `isReadManyFilesResult` type guard to `packages/core/src/tools/tools.ts` to improve typing for structured tool results.
- Fixed an incomplete test case in `DenseToolMessage.test.tsx` to properly simulate expansion via context instead of missing mouse events.

packages/cli/src/ui/utils/toolLayoutUtils.ts

@@ -17,7 +17,7 @@ import { CoreToolCallStatus } from '@google/gemini-cli-core';
  */
 export const TOOL_RESULT_STATIC_HEIGHT = 1;
 export const TOOL_RESULT_ASB_RESERVED_LINE_COUNT = 6;
-export const TOOL_RESULT_STANDARD_RESERVED_LINE_COUNT = 3;
+export const TOOL_RESULT_STANDARD_RESERVED_LINE_COUNT = 4;
 export const TOOL_RESULT_MIN_LINES_SHOWN = 2;
 
 /**