Add per-request AI logging, DB batch queue, WS entity updates, and UI polish

- log_thread.py: thread-safe ContextVar bridge so executor threads can log
  individual LLM calls and archive searches back to the event loop
- ai_log.py: init_thread_logging(), notify_entity_update(); WS now pushes
  entity_update messages when book data changes after any plugin or batch run
- batch.py: replace batch_pending.json with batch_queue SQLite table;
  run_batch_consumer() reads queue dynamically so new books can be added
  while batch is running; add_to_queue() deduplicates
- migrate.py: fix _migrate_v1 (clear-on-startup bug); add _migrate_v2 for
  batch_queue table
- _client.py / archive.py / identification.py: wrap each LLM API call and
  archive search with log_thread start/finish entries
- api.py: POST /api/batch returns {already_running, added}; notify_entity_update
  after identify pipeline
- models.default.yaml: strengthen ai_identify confidence-scoring instructions;
  warn against placeholder data
- detail-render.js: book log entries show clickable ID + spine thumbnail;
  book spine/title images open full-screen popup
- events.js: batch-start handles already_running+added; open-img-popup action
- init.js: entity_update WS handler; image popup close listeners
- overlays.css / index.html: full-screen image popup overlay
- eslint.config.js: add new globals; fix no-redeclare/no-unused-vars for
  multi-file global architecture; all lint errors resolved

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

static/index.html

@@ -33,6 +33,15 @@
 <!-- Slide-in toast notification; text set by toast() in js/helpers.js -->
 <div class="toast" id="toast"></div>
 
+<!-- Full-screen image popup: shown when user clicks a book spine or title-page image.
+     Closed by clicking outside or the × button. -->
+<div id="img-popup" class="img-popup">
+  <div class="img-popup-inner">
+    <button class="img-popup-close" id="img-popup-close">×</button>
+    <img id="img-popup-img" src="" alt="">
+  </div>
+</div>
+
 <!-- SortableJS: drag-and-drop reordering for rooms, cabinets, shelves, and books -->
 <script src="https://cdn.jsdelivr.net/npm/sortablejs@1.15.2/Sortable.min.js"></script>
 
@@ -73,7 +82,7 @@
      with all action cases; accordion expand helpers. -->
 <script src="js/events.js"></script>
 
-<!-- render(), renderDetail(), loadConfig(), startBatchPolling(), loadTree(),
+<!-- render(), renderDetail(), loadConfig(), connectBatchWs(), loadTree(),
      and the bootstrap Promise.all([loadConfig(), loadTree()]) call. -->
 <script src="js/init.js"></script>