fix: confirm dirty tabs before batch close

[PathGao]

Fixes #242.

Summary

• Route Close Others and Close to the Right through the existing save/discard/cancel flow.
• Stop the batch immediately when a user cancels or a save fails, preserving all remaining tabs.

Validation

• node --test --import tsx scripts/batchCloseConfirmation.test.ts
• npm run check

[alecdotdev]

i think a prior PR may have created a conflict. just at work but ready to merge when resolved

[PathGao]

@alecdotdev Thanks — I rebased #243 onto the current master and resolved the conflict while preserving the window-targeted listeners from #214. Its CI is running now.

Suggested merge order:

1. ci: gate releases on complete platform artifacts #241 — already clean, with the full platform build matrix passing.
2. fix: confirm dirty tabs before batch close #243 — once this current CI run passes.
3. I will then rebase and submit the remaining independent reliability fixes one at a time: fix: constrain theme and image file paths #249 (path/input hardening), fix: ignore stale preview renders #254 (stale preview renders), fix: guard viewer initialization after disposal #258 (viewer disposal), and fix: recover from interrupted session restores #260 (interrupted restore recovery).

I would hold #225 and #226 for now. They are larger feature expansions still conflicted on the old #214 stack; after the independent fixes, I plan to do the no-behavior-change session/runtime componentization separately, then rebuild or rebase those features on the stable boundary.