feat(ui): implement compact tool output and structured tool results

This commit introduces the compactToolOutput feature to optimize terminal vertical space usage for common, high-volume tools.

1. Compact Tool Output UI:
- Added DenseToolMessage component for rendering compact, single-line tool summaries.
- Updated ToolGroupMessage to detect contiguous compact tools and render them with stitched borders for a streamlined look.
- Added Ctrl+O shortcut in AppContainer to toggle full expansion of tool results from the last turn.
- Implemented useGeminiStream border logic to correctly render borders around dense sections.

2. Core Tool Structured Results:
- grep: Updated to return GrepResult with matches, file paths, and line numbers instead of a raw formatted string.
- ls (list_directory): Updated to return ListDirectoryResult with an array of files.
- read_many_files: Updated to return ReadManyFilesResult with read files, skipped files, and reasons.
- Modified ToolResultDisplay and isStructuredToolResult type guards to support these new structured interfaces.

3. User Settings & Documentation:
- Added compactToolOutput to the UI settings schema (default: true).
- Updated configuration docs and schema to reflect the new setting.
- Adjusted compact subview line limits (COMPACT_TOOL_SUBVIEW_MAX_LINES).

test(cli): refine settings and tool action mocks to resolve test rig regressions

This update addresses incomplete settings store contracts and default state mismatches that caused snapshot runtime errors and verification failures in compact tool output tests.

1. Settings Mock Completeness:
- Updated `createMockSettings` in `mockConfig.ts` to include required functional methods (`subscribe`, `getSnapshot`, `setValue`) to satisfy React's `useSyncExternalStore` contract. This resolves "store.getSnapshot is not a function" errors in snapshot tests.

2. Tool Actions Provider Configuration:
- Modified `renderWithProviders` to accept a `toolActions` options object, allowing individual tests to inject specific tool expansion states.
- Changed the default mock for `isExpanded` from `true` to `false` to align with the application's default behavior (collapsed outputs) in alternate buffer mode.

3. Test Refactoring:
- Refactored `ToolGroupMessage.compact.test.tsx` to use the standardized `createMockSettings` utility rather than a manual generic object, ensuring proper context evaluation during rendering.

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.

docs/cli/settings.md

@@ -59,6 +59,7 @@ they appear in the UI.
 | Hide Tips                            | `ui.hideTips`                          | Hide helpful tips in the UI                                                                                                                                       | `false`  |
 | Escape Pasted @ Symbols              | `ui.escapePastedAtSymbols`             | When enabled, @ symbols in pasted text are escaped to prevent unintended @path expansion.                                                                         | `false`  |
 | Show Shortcuts Hint                  | `ui.showShortcutsHint`                 | Show the "? for shortcuts" hint above the input.                                                                                                                  | `true`   |
+| Compact Tool Output                  | `ui.compactToolOutput`                 | Display tool outputs (like directory listings and file reads) in a compact, structured format.                                                                    | `false`  |
 | Hide Banner                          | `ui.hideBanner`                        | Hide the application banner                                                                                                                                       | `false`  |
 | Hide Context Summary                 | `ui.hideContextSummary`                | Hide the context summary (GEMINI.md, MCP servers) above the input.                                                                                                | `false`  |
 | Hide CWD                             | `ui.footer.hideCWD`                    | Hide the current working directory in the footer.                                                                                                                 | `false`  |