Productivity features, UI translations, local email translation

- Snooze (with a Snoozed folder), keyboard shortcuts with a Settings
  section, mail templates (Compose > More > Templates), a Subscriptions
  folder with bulk unsubscribe/delete, and tracker blocking with a
  Privacy toggle (on by default)
- Own dialogs instead of browser popups; emoji picker in compose; compose
  windows survive a visit to Settings
- Sentence completion learned from the user's sent mail (no AI)
- Interface in English and Polish (one file per language, English as the
  fallback), picked from the browser on first run, then kept
- Email translation on the server via LibreTranslate: Translate button
  and "Translate to...", messages in several languages translated part
  by part, names/addresses/emoji/file names/phone numbers kept, an
  animated line while translating
- Antispam "Mark as spam" loads with the message, not when the menu opens

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/lib/useKeyboardShortcuts.ts

@@ -1,15 +1,28 @@
 import { useEffect, useRef } from "react";
 
-// Keyboard shortcuts (SPEC §9.4). Ignores keystrokes while typing in inputs,
-// except Escape. Supports the `g i` chord (go to inbox).
+// Keyboard shortcuts (SPEC §9.4; the list users see is lib/shortcuts.ts).
+// Ignores keystrokes while typing in inputs, except Escape. "g" starts a
+// two-key sequence (g i = Inbox). With `enabled` false only Escape works.
 export interface Shortcuts {
+  enabled?: boolean;
   onSearch?: () => void;
   onCompose?: () => void;
   onReply?: () => void;
   onReplyAll?: () => void;
   onForward?: () => void;
   onArchive?: () => void;
+  onTrash?: () => void;
+  onTogglePin?: () => void;
+  onSnooze?: () => void;
+  onMarkRead?: () => void;
+  onMarkUnread?: () => void;
+  onBack?: () => void;
   onGoInbox?: () => void;
+  onGoSnoozed?: () => void;
+  onGoDrafts?: () => void;
+  onGoSent?: () => void;
+  onGoSubscriptions?: () => void;
+  onHelp?: () => void;
   onEscape?: () => void;
   onNext?: () => void;
   onPrev?: () => void;
@@ -18,7 +31,7 @@ export interface Shortcuts {
 function isTyping(el: EventTarget | null): boolean {
   if (!(el instanceof HTMLElement)) return false;
   const tag = el.tagName;
-  return tag === "INPUT" || tag === "TEXTAREA" || el.isContentEditable;
+  return tag === "INPUT" || tag === "TEXTAREA" || tag === "SELECT" || el.isContentEditable;
 }
 
 export function useKeyboardShortcuts(shortcuts: Shortcuts): void {
@@ -33,49 +46,54 @@ export function useKeyboardShortcuts(shortcuts: Shortcuts): void {
         s.onEscape?.();
         return;
       }
-      if (isTyping(e.target)) return;
+      if (s.enabled === false || isTyping(e.target)) return;
       if (e.metaKey || e.ctrlKey || e.altKey) return;
 
+      const run = (fn: (() => void) | undefined) => {
+        if (!fn) return;
+        e.preventDefault();
+        fn();
+      };
+
       if (pendingG.current) {
         pendingG.current = false;
-        if (e.key === "i") {
-          e.preventDefault();
-          s.onGoInbox?.();
+        const go: Record<string, (() => void) | undefined> = {
+          i: s.onGoInbox,
+          z: s.onGoSnoozed,
+          d: s.onGoDrafts,
+          t: s.onGoSent,
+          b: s.onGoSubscriptions,
+        };
+        if (e.key in go) {
+          run(go[e.key]);
           return;
         }
       }
 
-      switch (e.key) {
-        case "/":
-          e.preventDefault();
-          s.onSearch?.();
-          break;
-        case "c":
-          s.onCompose?.();
-          break;
-        case "r":
-          s.onReply?.();
-          break;
-        case "a":
-          s.onReplyAll?.();
-          break;
-        case "f":
-          s.onForward?.();
-          break;
-        case "e":
-          s.onArchive?.();
-          break;
-        case "j":
-          s.onNext?.();
-          break;
-        case "k":
-          s.onPrev?.();
-          break;
-        case "g":
-          pendingG.current = true;
-          window.setTimeout(() => (pendingG.current = false), 800);
-          break;
+      // Shift+letter arrives as the capital letter.
+      const actions: Record<string, (() => void) | undefined> = {
+        "/": s.onSearch,
+        "?": s.onHelp,
+        c: s.onCompose,
+        r: s.onReply,
+        a: s.onReplyAll,
+        f: s.onForward,
+        e: s.onArchive,
+        "#": s.onTrash,
+        s: s.onTogglePin,
+        b: s.onSnooze,
+        I: s.onMarkRead,
+        U: s.onMarkUnread,
+        u: s.onBack,
+        j: s.onNext,
+        k: s.onPrev,
+      };
+      if (e.key === "g") {
+        pendingG.current = true;
+        window.setTimeout(() => (pendingG.current = false), 1000);
+        return;
       }
+      if (e.key in actions) run(actions[e.key]);
     };
     window.addEventListener("keydown", handler);
     return () => window.removeEventListener("keydown", handler);