fix: codebase audit fixes — indexes, daily_rate, anomaly key, CSRF, chat pruning, shopping_name

## v1.7.6

- DB: fix shopping_name Pi→Piadina, Grana→Formaggio, Prosciutto cotto→Affettato, Panna acida→Panna
- DB: composite indexes idx_transactions_type_date + idx_transactions_pid_type_undone (+ migration)
- PHP: daily_rate uses first_in→last_activity window (not first_in→now)
- PHP: anomaly dismiss key uses product_id+direction (stable, not product_id+round(expected))
- PHP: smart shopping — products exhausted within 14 days bypass token/family suppression
- PHP: chat pruning — DELETE messages beyond 200 after each chatSave()
- PHP: getStats() — 5 queries → 1 consolidated query with subselects
- PHP: bringCleanupObsolete — 300ms delay between bulk removals
- PHP: CSRF guard — POST write actions require X-EverShelf-Request:1 or Content-Type:application/json
- JS: api() — sends X-EverShelf-Request:1 on all POST requests
- JS: _opLog — prunes entries older than 30 days in addition to 200-entry cap

index.html

@@ -67,7 +67,7 @@
         <!-- Title — left-aligned; grows to fill space -->
         <div class="header-title-wrap">
             <h1 class="header-title" onclick="showPage('dashboard')">
-                <img src="assets/img/logo/logo_icon.png" alt="" class="header-logo-icon" aria-hidden="true" /><span data-i18n="nav.title">EverShelf</span><span class="header-version">v1.7.5</span>
+                <img src="assets/img/logo/logo_icon.png" alt="" class="header-logo-icon" aria-hidden="true" /><span data-i18n="nav.title">EverShelf</span><span class="header-version">v1.7.6</span>
             </h1>
             <!-- Update badge — shown alongside title, never replaces it -->
             <span class="header-update-badge" id="header-update-badge" style="display:none"></span>