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/js/helpers.js

@@ -6,16 +6,25 @@
  * Provides: esc(), toast(), isDesktop()
  */
 
+/* exported esc, toast, isDesktop */
+
 // ── Helpers ─────────────────────────────────────────────────────────────────
 function esc(s) {
-  return String(s ?? '').replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;').replace(/"/g,'&quot;');
+  return String(s ?? '')
+    .replace(/&/g, '&amp;')
+    .replace(/</g, '&lt;')
+    .replace(/>/g, '&gt;')
+    .replace(/"/g, '&quot;');
 }
 
 function toast(msg, dur = 2800) {
   const el = document.getElementById('toast');
-  el.textContent = msg; el.classList.add('on');
+  el.textContent = msg;
+  el.classList.add('on');
   clearTimeout(toast._t);
   toast._t = setTimeout(() => el.classList.remove('on'), dur);
 }
 
-function isDesktop() { return window.innerWidth >= 768; }
+function isDesktop() {
+  return window.innerWidth >= 768;
+}