fix(permissions): keep Undo stack above window bottom

[ewen-poch]

Problem

On Windows, closing the permission surface could leave the Undo snackbar below the visible window. The fixed stack used the shared Radix ScrollArea with a full-height viewport, but its root only had a maximum height. Without a definite parent height, the bottom-anchored content could be laid out past the viewport.

Proposed change

• Replace the full-height Radix viewport with a content-sized native overflow container.
• Preserve the existing bottom safe-area offset, maximum stack height, overscroll behavior, and per-receipt interactions.
• Add a regression test that locks down the intrinsic-height scroll structure after Settings closes.

Scope and non-goals

This change only affects the permission Undo stack layout. It does not change grant revocation, restoration, expiry, queueing, or other shared ScrollArea consumers.

Acceptance criteria and validation

The checks below ran against the final material implementation:

• Undo remains bottom-anchored and scrolls within the visible viewport -> npm test -- src/renderer/src/components/PermissionUndoSnackbar.test.tsx -> passed, 6/6 tests.
• Changed files satisfy ESLint/Prettier rules -> npx --no-install eslint src/renderer/src/components/PermissionUndoSnackbar.tsx src/renderer/src/components/PermissionUndoSnackbar.test.tsx -> passed.
• Patch has no whitespace errors -> git diff --check -> passed.
• Repository lint -> npm run lint -> passed with 0 errors; unrelated baseline warnings remain.
• Repository typecheck -> npm run typecheck -> blocked because this worktree does not have the lockfile dependencies fflate and tiff installed.
• Full test suite -> npm test -> not completed in the restricted sandbox; localhost-listening tests failed with EPERM and the runner was terminated after five minutes.

Uncovered risk: the structural regression is deterministic, but the final layout has not been visually exercised on a Windows Electron runtime.

Review focus

Please verify that the content-sized overflow container keeps single and queued Undo receipts above the bottom edge without changing restore, dismiss, expiry, or modal interaction behavior.

[github-actions]

Codex Review

Verdict: mergeable

No actionable findings.

Summary: Static inspection found no concrete merge-blocking defect in the pull request changes.