feat(calibre): add Readest calibre plugin to push books and metadata (#4918)

* feat(calibre): add Readest calibre plugin to push books and metadata (#4863)

Add apps/readest-calibre-plugin, a calibre GUI plugin that uploads
selected books with their metadata into the user's Readest cloud
library, modeled on BookFusion's open-source plugin.

- Selective manual push from the calibre toolbar with per-book status
  (uploaded / updated / up to date / failed) and quota handling
- Books are content-addressed with the same partial MD5 as the apps,
  so re-pushing updates the existing entry instead of duplicating;
  metadata edits re-push without re-uploading the file
- Metadata mapping includes series, tags, identifiers and optional
  calibre custom columns; carries over server-side fields (progress,
  reading status, grouping, cover) that POST /sync would null out
- Auth mirrors readest.koplugin and the desktop app: email/password
  plus browser OAuth (Google/Apple/GitHub/Discord) through a localhost
  callback server with the fragment-to-query relay
- Pure-logic modules (api.py, wire.py, oauth.py) are calibre-free and
  covered by 56 unit tests (make test); make zip builds the plugin

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* ci(release): package readest-calibre-plugin in releases

Mirror the KOReader plugin packaging: a build-calibre-plugin job stamps
PLUGIN_VERSION in __init__.py with the release version from
apps/readest-app/package.json, builds the zip via make, and uploads
Readest-<version>.calibre-plugin.zip to the GitHub release. The version
committed in git stays a development placeholder.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* chore(agent): add calibre plugin project memory

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* feat(calibre): embed metadata in OPF and dedupe by calibre uuid

Rework book identity so metadata can be embedded into the uploaded file
without creating duplicates, as requested in review:

- Embed calibre metadata (including custom columns) into a temporary
  copy of the book file at upload time via calibre's set_metadata; the
  library file is never modified
- Dedupe by the calibre book uuid carried in the entry's metadata
  identifier, which survives file-byte changes, with a live-row
  preference when both hash and uuid match rows
- Detect file content changes via calibreSourceHash, the raw library
  file fingerprint stored in the pushed metadata, so detection works
  from any machine; v1 rows fall back to book_hash which equals the
  raw hash for them
- A changed file now replaces the old entry in one sync push (new row
  with carried-over reading status, grouping, progress and created
  date, plus a tombstone for the old row) and deletes the old cloud
  files to reclaim quota
- Metadata-only edits still update the library entry without
  re-uploading the file

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* chore(calibre): set copyright holder to Bilingify LLC

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/readest-app/.claude/memory/MEMORY.md

@@ -114,6 +114,7 @@
 - OPDS: [Firefox strict-XML #4479](opds-firefox-strict-xml-4479.md) junk after `</feed>` slice to last close; [JSON search #4502](opds2-json-search-4502.md) expand `{?query}` BEFORE resolveURL; [HTML desc #4503](opds-html-description-4503.md) decode-once+sanitize; [self-link meta #4749](opds-self-link-metadata-4749.md) `rel:self` deref; [popular dedup #4782](opds-popular-catalog-dedup-4782.md)
 - [D-pad Navigation](dpad-navigation.md) — Android TV remote / arrow-key nav
 - [koplugin cover upload (#4374)](koplugin-cover-upload.md) — `extractLocalCover` via `getCoverImage`
+- [Calibre plugin push #4863](calibre-plugin-push-4863.md) apps/readest-calibre-plugin; OAuth localhost relay + /sync carry-over
 ## Library Fixes
 - [Book action platform surfaces](book-actions-platform-surfaces.md) — context menu Tauri-desktop-only; cross-platform
 - [Tauri menu append race (#4389)](tauri-menu-append-race-4389.md) — single `await Menu.new({ items })`