feat(studio): reopen the last closed query tab - #767

Description

Accidentally closing an unsaved query can now be undone with the "Reopen last closed tab" button next to the new-tab button. It restores the last closed tab's name, text and query language in both Studio and StudioWorkspace, without adding a close confirmation.

Closes #747.

Changes Made

• Keep one closed-tab snapshot in the shared tab manager, scoped to the current connection and cleared after reopening or switching connections.
• Reopen with a fresh ID and cleared execution state so a late response from the closed tab cannot overwrite the restored query.
• Keep the existing last-tab safeguard and active-tab fallback. Preserve queued updates to other tabs during close.
• Add an accessible, disabled-when-unavailable reopen control and document the recovery lifetime: until another tab closes, the connection changes, or the page reloads.

Testing

• TDD: three recovery regressions failed before implementation.
• bun run test:hooks --isolate --pass-with-no-tests -t 'useTabManager': 35 passed.
• Project-isolated component run targeting StudioTabBar: 29 passed.
• Passed locally: format, lint, typecheck, knip, readme:check, chart:check, channels:showcase:check, security:check. The final functional-state-update adjustment was followed by the 35-test hook run and diff review.
• build, build:lib and attw passed on clean commit fb284404db49839c867a78fbb81551780294a6b2.
• Full local bun run test, coverage and app E2E were not run: this Windows host lacks Helm/chart dependencies and working Docker; existing SQLite cleanup also encounters Windows file locks. CI must verify the full suite and 100% line coverage.

Environment: Windows, Node.js 24.18.1, Bun 1.4.2.

Checklist

• Claimed and linked the issue, reviewed the diff, updated documentation and added regression tests.
• Required CI test job passes the 100% line-coverage gate.

Additional Notes

AI-assisted implementation and validation using Codex. Recovery is an in-memory single-tab history; query results and in-flight execution are intentionally not restored. No dependencies, persistence-format changes or provider changes.