Introduces the per-feature REST bridges pattern with a thin
Rest_Controller that registers routes only when the modernization
filter is on. Capabilities_Bridge proxies /sites/{id}/rewind to
expose hasBackupPlan + planSlug for the React layer.

Gates mounts inside DashboardLayout between the QueryClientProvider
and the body slot. Top-to-bottom: loading → not-connected →
secondary-admin → no-plan → children. All three routes inherit
gating for free.

Connection state comes from window.JP_CONNECTION_INITIAL_STATE,
emitted inline on the modernized Backup admin page from
class-jetpack-backup.php (the modernized enqueue path skips the
legacy render_script call, so we need to put the global up ourselves).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Replaces useMockActivityLog with useActivityLog backed by an
apiFetch -> bridge -> WPCOM /sites/{id}/activity/rewindable chain.
A small normalize/activity-log.ts maps WPCOM's rewindable-activity
shape (gridicon, content.text, object.backup_stats) onto the
ActivityItem discriminated union the UI already consumes.

The hook returns `totalItems` in addition to `totalPages` because the
trunk ActivityList drives DataViews' `paginationInfo` from both. The
WPCOM endpoint doesn't accept `page` or `search`, so the hook fetches
a 100-item window and filters/paginates client-side — DataViews
remains the single source of truth for the visible slice.

Overview's right-pane lookup swaps from the fixture's
findActivityById to getCachedActivityById, which reads the same
single-window cache the list populates. The default selection
(newest backup) is derived from the cache the same way.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Adds the File_Browser_Bridge (ls + path-info + file-content), each
proxying WPCOM /sites/{id}/rewind/backup/* via as_user. The file-content
endpoint resolves the signed stream URL server-side and caps the
returned body at 64 KB so previews can't balloon the REST response.

React side: useFileTree replaces useMockFileTree, useFileContents
replaces the static findContents() fixture lookup. The rewindId prop
on FileBrowser is now actually consumed and threaded through every
NodeRow so each folder fetches its own children.

FileInfoCard no longer reads metadata from fixture nodes — usePathInfo
fetches size + mime + last-modified for the open file, and
useFileContents pulls the preview body only when the mime type is
text-shaped. FileNodeFile's metadata fields drop to optional since
WPCOM's /ls endpoint only returns name + type.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

useDownload replaces useMockDownload, driving the same
idle → submitting → progress → success | error state machine off
a TanStack useMutation (initiate) + polled useQuery (status).
The bridge proxies WPCOM's /rewind/backups/{rewindId}/prepare-download
and /rewind/backups/{rewindId}/downloads/{id} endpoints.

The screen now derives its "download point" timestamp directly from
the rewindId (it's unix-seconds) instead of resolving it through the
activity-log fixture — Download / Restore can stand alone without
relying on Overview having populated its cache first.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

useRestore replaces useMockRestore, driving the same state machine off
a TanStack useMutation (initiate) + polled useQuery (status). The
bridge proxies WPCOM's v1 /activity-log/{site}/rewind/to/{rewindId}
and /rewind/{restoreId}/restore-status endpoints, with the verbatim
comment explaining why the rewind endpoint must sign as_user
(blog-token auth is rejected by WPCOM with "That API call is not
allowed for this account").

Same rewindId → unix-seconds derivation as the Download screen, so
Restore stands alone without depending on Overview's cache.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Removes the last mock-mode artifacts: useIsMockMode, the dev banner
component, the four mock hooks, the three fixture files, and the
<DevModeBanner /> mount inside DashboardLayout. The modernized
Backup dashboard now only renders real data via the jetpack/v4/*
bridges, with <Gates> handling the not-connected and no-plan
fallbacks.

This completes Phase 2 of the Backup modernization.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

One test class per bridge:
- Rest_Capabilities_Bridge_Test (2 tests, 2 assertions)
- Rest_Activity_Log_Bridge_Test (2 tests, 2 assertions)
- Rest_File_Browser_Bridge_Test (4 tests, 4 assertions)
- Rest_Download_Bridge_Test (3 tests, 4 assertions)
- Rest_Restore_Bridge_Test (3 tests, 4 assertions)

Each class confirms the routes only register when the modernization
filter is on and that the manage_options permission_check rejects
subscriber-level access with a 403. Upstream WPCOM calls aren't
exercised here — they need network and a real connection.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

…es + review cleanup

The RestoreItemsChecklist selection was collected into local state on the
Restore and Download screens but never sent to the bridge, so an unchecked
"Plugins" or "Themes" was silently restored anyway. Thread `RestoreItems`
through `useRestore` / `useDownload` → `initiateRestore` / `initiateDownload`
as the mutation variable, and surface it to the bridges as `data: { types }`
(the keys already match WPCOM's `types` payload).

Also clears the review suggestions from the same pass:

* `useFileContents` browser path now UTF-8 encodes via TextEncoder before
  btoa, so non-ASCII manifest paths (accented or CJK upload filenames)
  no longer throw InvalidCharacterError.
* `useConnection` drops its empty-deps useMemo and reads
  JP_CONNECTION_INITIAL_STATE on every render — single property lookup,
  removes any risk of capturing a pre-emit empty snapshot if load order
  ever shifts.
* `query-client.ts` docstring corrected: each wp-build route is its own
  bundle so the cache is per-route, not shared across navigation. The
  design doesn't depend on cross-route reuse, but the comment shouldn't
  claim otherwise.
* `Restore_Bridge::initiate_restore` returns the same user-facing
  "Could not start the backup restore." string in both failure branches
  instead of the diagnostic "Restore response missing restore id."
* `Activity_Log_Bridge` drops the declared-but-unused `aggregate`,
  `after`, `before` args (and mirrors the cleanup in
  `data/api/activity-log.ts`'s FetchArgs) — the hook only ever passes
  `number`.
* Download success link gains `download` + `rel="noreferrer"` so the
  signed URL triggers a download instead of navigating away when WPCOM
  omits Content-Disposition.

PHP + JS tests pass; phan unchanged (only the pre-existing build/ artifact
warning); eslint clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>