Implemented UI Status Bar for Claude CLI

[xgsa]

Rationale: when working with Claude Code it is useful to control context usage, limits and other important parameters. There are CLI plugins that provide such functionality, however having this information in GUI form looks nicer and is more flexible.

Implementation details and architectural decisions can be found in doc/claude-status-bar.md.

Here is how it looks like:

There are also additional information in tooltips:

Status bar handles different view widths in a nice way:

There are preferences to configure status bar layout:

[xgsa]

@eilonwy06, could you please try it out and give a feedback?
The major points to check:

• overall status bar look on your build (OS Windows, dark theme -- should be OK, but need to verify);
• different view width handling;
• segment tooltips;
• preferences.

Also I need your help to build windows & macos versions of the rust library.

Possibly it worth reorganizing preferences on a few pages. Maybe you have other ideas or data to add. Also in theory this status bar could be also used on Claude GUI view (or maybe its backend part with another UI component).

Also in this PR I decided to commit the feature implementation plan we worked on with Claude, so the feature architecture, decisions made and approaches rejected are more explicit. We could follow this approach if you also think it is useful.