fix(webapp): keep the branches list query string when archiving a branch (#4724)

<!-- ccr-slack-attribution -->
_Requested by **Iss** · [Slack
thread](https://triggerdotdev.slack.com/archives/C045W9WM3E1/p1787161814493949)_

**Before:** archiving a branch dropped the query string on the way back
to the branches list, so the list reset to page 1. Working down a long
list meant re-navigating to the page you were on after every archive.

**After:** you land back on the exact page you archived from, with
`page`, `search` and `showArchived` intact.

The archive action now redirects to the page the request came from
instead of rebuilding a bare branches path.

## How

The archive dialog already submits the page it was opened from as a
hidden `redirectPath` field (`${location.pathname}${location.search}`),
and the failure path already redirected to it — only the success path
ignored it and rebuilt the path with `branchesPath`/`branchesDevPath`,
which have no query string. Both paths now redirect to the submitted
path, run through the existing `sanitizeRedirectPath` helper to keep the
redirect same-origin (the same idiom used by
`resources.batches.$batchId.check-completion`).

## ✅ Checklist

- [x] I have followed every step in the [contributing
guide](https://github.com/triggerdotdev/trigger.dev/blob/main/CONTRIBUTING.md)
- [x] The PR title follows the convention.
- [x] I ran and tested the code works

---

## Testing

Three files change:

- `apps/webapp/app/routes/resources.branches.archive.tsx` — the fix.
- `apps/webapp/test/archiveBranchRedirect.test.ts` — new test that
drives the archive action and asserts the redirect `Location`: the query
string survives on both success and failure, and an off-origin
`redirectPath` falls back to `/`. Reverting the fix makes two of the
three cases fail, so the test covers the regression.
- `.server-changes/archive-branch-keeps-list-page.md` — release-note
entry, since this is a user-facing server-only change.

Also ran `pnpm run typecheck` and `oxlint` for `apps/webapp` — both
clean.

---

## Changelog

Archiving a branch now returns you to the same page of the branches list
instead of resetting it to page 1.

---

## Screenshots

_None — no visual change._

---------

Co-authored-by: Claude <noreply@anthropic.com>