fix(cli): consolidate Ctrl+O expansion toggle logic between shell tool and compact tool output; resolve rendering issues

Interaction:
- Unify SHOW_MORE_LINES (Ctrl+O) handler in AppContainer to atomically toggle height constraints and compact tool expansions.
- Update DenseToolMessage toggle text to "[click here to show/hide details]" for improved clarity.

Rendering:
- Adjust ToolGroupMessage and HistoryItemDisplay layout logic to correctly manage margins and spacing, especially after thinking blocks.
- Fix "Double Empty Line" issue by removing redundant top margins from the first tool in a group.
- Fix ToolStickyHeaderRegression test expectations to correctly account for 3-line headers.
- Update snapshots across multiple components to reflect layout and text refinements.
- Update generated docs and setting artifacts

Structural:
- Shifts large logic blocks within AppContainer.tsx to resolve functional dependencies related to keyboard handlers, user feedback events, and window titles.
- Hoist tool expansion state to AppContainer for centralized control and synchronized layout updates.
- Refactor ToolActionsContext.test.tsx to use real React state for verified behavior.

docs/cli/settings.md

@@ -154,7 +154,6 @@ they appear in the UI.
 | Model Steering             | `experimental.modelSteering`             | Enable model steering (user hints) to guide the model during tool execution.                                                                              | `false` |
 | Direct Web Fetch           | `experimental.directWebFetch`            | Enable web fetch behavior that bypasses LLM summarization.                                                                                                | `false` |
 | Topic & Update Narration   | `experimental.topicUpdateNarration`      | Enable the experimental Topic & Update communication model for reduced chattiness and structured progress reporting.                                      | `false` |
-| Enable Gemma Model Router  | `experimental.gemmaModelRouter.enabled`  | Enable the Gemma Model Router. Requires a local endpoint serving Gemma via the Gemini API using LiteRT-LM shim.                                           | `false` |
 
 ### Skills