Chat mode, phase 2: local history, answer actions, motion polish

- Conversations in a versioned IndexedDB store (freezmo-chat v1, zod
  validated with the same schema backup/sync use, capped at 100 x 300).
  Settled turns persist (question always; answer when produced, partial
  stops included); ?c=<id> keeps reloads on the conversation via
  history.replaceState (no router round-trip mid-chat).
- History UI: desktop column, phone sheet (spring, backdrop, Escape),
  auto titles from the first question, inline rename, delete with an
  Undo toast, diacritic-folding search over titles and message text.
  Scope and model are remembered per conversation; history is readable
  offline.
- Assistant actions: Turn into flashcards (New deck with the answer as
  notes, landing on the options step - deck seed gained step) and Save
  to notes (appends to the single scoped deck, trimmed at 40k).
- Chats travel in the backup export (preview counts them) and in the
  encrypted sync payload; still never the key.
- Motion from lib/motion.ts: message fade-up, sheet springs for the
  model/context/history sheets, 150ms composer height transition, all
  skipped under reduced motion.
- Tests: chat suite 63 -> 89 checks (history, reload, rename/search/
  delete/undo, actions, export, two-device sync round-trip, offline,
  desktop panel). Full set: 12/12 suites, 513 checks. SW -> freezmo-v33.

Also: tests/model-compare.mjs benchmark (diagnostic) for deciding the
default text model on numbers; defaults unchanged.

components/chat/MessageRow.tsx

@@ -7,7 +7,7 @@ import { Markdown } from "./Markdown";
 import { ThinkingRow } from "./ThinkingRow";
 import { Button } from "@/components/ui";
 import { ModelErrorActions } from "@/components/ModelErrorActions";
-import { PencilIcon, RefreshIcon } from "@/components/icons";
+import { PencilIcon, PlusIcon, RefreshIcon, SparklesIcon } from "@/components/icons";
 import { useI18n } from "@/lib/i18n";
 import type { ChatMessage } from "@/lib/chat";
 
@@ -24,6 +24,8 @@ export function MessageRow({
   onRegenerate,
   onEdit,
   onRetry,
+  onToFlashcards,
+  onSaveNotes,
 }: {
   message: ChatMessage;
   streaming?: boolean;
@@ -33,6 +35,8 @@ export function MessageRow({
   onRegenerate?: () => void;
   onEdit?: () => void;
   onRetry?: () => void;
+  onToFlashcards?: () => void;
+  onSaveNotes?: () => void;
 }) {
   const { t } = useI18n();
 
@@ -108,6 +112,26 @@ export function MessageRow({
               {t("chat.regenerate")}
             </button>
           ) : null}
+          {onToFlashcards ? (
+            <button
+              type="button"
+              onClick={onToFlashcards}
+              className="flex items-center gap-1.5 rounded-xl border border-[var(--glass-border)] bg-[var(--surface-strong)] px-2.5 py-2 text-[12px] font-medium text-[var(--text-muted)] transition hover:bg-[var(--hover)] hover:text-[var(--text)]"
+            >
+              <SparklesIcon className="size-3.5" />
+              {t("chat.toFlashcards")}
+            </button>
+          ) : null}
+          {onSaveNotes ? (
+            <button
+              type="button"
+              onClick={onSaveNotes}
+              className="flex items-center gap-1.5 rounded-xl border border-[var(--glass-border)] bg-[var(--surface-strong)] px-2.5 py-2 text-[12px] font-medium text-[var(--text-muted)] transition hover:bg-[var(--hover)] hover:text-[var(--text)]"
+            >
+              <PlusIcon className="size-3.5" />
+              {t("chat.saveToNotes")}
+            </button>
+          ) : null}
           {message.model ? <span className="text-[11px] text-[var(--text-subtle)]">{message.model}</span> : null}
         </div>
       ) : null}