fix(desktop): restore right workbar scrolling

[liuxiaocs7]

Summary

• Constrain the shared right Workbar overlay to one shrinkable grid row so tall faces stay within the viewport and retain their local scroll containers.
• Add a Changes Storybook regression that reveals the second file page and proves the panel can change scrollTop.
• This restores scrolling for shared right-side faces such as Changes and Trace without changing their individual scroll ownership.

Fixes #4999

Verification

• Regression Story reproduced before the fix: clientHeight=1305, scrollHeight=1305, scrollTop=0.
• After the fix, Changes measured clientHeight=868, scrollHeight=1289, and scrolled 421px; Trace measured clientHeight=868, scrollHeight=1416, and scrolled 548px.
• npm run build-storybook -w @maka/desktop
• npm run smoke:storybook -w @maka/desktop — 326 stories, 353 theme renders
• npm run typecheck:stories -w @maka/desktop
• npm run check:architecture -w @maka/desktop
• npm run build:renderer -w @maka/desktop
• npx biome check apps/desktop/stories/session-workbar.stories.tsx apps/desktop/src/renderer/styles/workbar/shell.css
• git diff --check

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope:

Codex diagnosed the shared Grid sizing regression, implemented the CSS fix and Storybook regression, ran verification, and prepared the issue, commit, and PR description.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

[me2seeks]

Automated review by OpenAI Codex, operated by me2seeks, at 623ac3e5533f3b69263e6a1c94681a1d43a63ca8. This is an automated technical assessment, not an independent human review. Approval is submitted at the operator's explicit direction.

No actionable findings. Traced WorkbarPanel -> Astryx Section inner height:100% wrapper -> review panel overflow owner. A headless Chromium layout reproduction using the exact before/after shell CSS and those production sizing rules changes the tall face from clientHeight=1600, scrollTop=0 to clientHeight=560, scrollTop=500. The story now expands the second page and asserts actual scrolling. #4967 overlaps the same row constraint and will need reconciliation after this lands.

1. Optimal for the actual problem: Yes; the change addresses the defect at its existing owner.
2. Production code that can be deleted: None identified.
3. Low-quality tests that can be deleted or replaced: None identified.
4. Deeper refactor: No deeper refactor is needed.
5. Ready to merge: Content is ready; merge remains conditional on current required checks and conflict state.
6. Residual risks / verification: Local Chromium sizing reproduction passed; hosted test is SUCCESS at this head. The complete Storybook and Electron suites were not rerun locally. User-visible scrolling changes; material protected-area changes require independent human review under CONTRIBUTING.md.