Restore Workbench tab strip and Folder Merge path footers

[baseGame]

Summary

• Restore multi-session tab-strip / tab-chip chrome from crushed 11px buttons toward capture-scale ~22px CSS (title-band metric ~22.5 at DPR≈2); padding/borders aligned.
• Raise WorkbenchShell workbench-titlebar from 10px to 22px; mark data-shell-density="capture-1to1".
• Fix Folder Merge merge-path-footer crush (8px → 20px / 11px, matching PathMetaFooter rhythm).

Test plan

• Vitest shellChromeDensity, syncMergeChromeDensity, full src/styles/, AppLayout.test.ts
• Pre-commit quality (prettier, eslint, stylelint, vue-tsc, rust fmt/clippy)
• Spot-check multi-tab window vs docs/assets/.../home.png, folder-compare.png, text-compare.png, folder-merge.png

Remaining divergences

• Captures are mostly single-session; exact multi-tab native tab glyph/spacing may still differ.
• Sync/Merge path footers still custom labels (not full PathMetaFooter stamps).
• Lucide vs native glyphs; Options dialog / Tol panels intentionally out of scope.