Chat mode, phase 1: grounded streaming chat over your notes

Entry points (no sixth tab): Ask in the Library header (desktop button,
phone icon), Ask about this deck in the deck menu, Ask a question on
study/homework results (compact result travels as context), and a Chat
row in the desktop sidebar. Phones get a full-screen route with back +
New chat; the tab bar steps aside.

- Client-side retrieval: chunk scoped decks (~800 tokens), BM25 against
  the question + recent turns, top chunks under ~7k tokens, each
  labelled with deck + section. Notes come from the deck's stored
  sourceText (already kept for Regenerate); decks without it fall back
  to generated content and the UI says so.
- Stateless server: /api/chat validates against the CHAT_MODELS
  allowlist, trims the history to ~6k tokens, caps context at ~9k and
  streams token/thinking/done/error NDJSON. /api/chat/extract reduces
  attachments to text through the existing vision step.
- UI: user bubbles + full-width assistant text, streaming with stop,
  auto-scroll that pauses with a jump-to-bottom button, safe markdown
  (React nodes, no HTML injection; KaTeX dynamically imported only when
  a message has math), Thinking row for reasoning, copy/regenerate/
  edit-and-resend, model + context pickers (last model remembered),
  composer with visualViewport keyboard handling, safe-area, 16px
  textarea, Enter-to-send on desktop.
- Usage-limit failures keep the draft and show the shared message with
  Settings/Ollama actions; stopping maps the reader abort to a clean
  stopped state; offline disables sending with a reason.
- Settings: Keep notes text for chat toggle; deck menu: Delete notes
  text. RATE_LIMIT_CHAT + CHAT_MODELS in .env.example and README.
- Tests: chat suite (63 checks, stub Ollama) wired into run-all.
  Full set: 12/12 suites, 487 checks. SW -> freezmo-v32.

Also: tests/model-compare.mjs (diagnostic) benchmarks two models on the
same notes (latency, repair rounds, activity types) so the gpt-oss vs
gemma default can be decided on numbers; defaults unchanged.

components/DeckCard.tsx

@@ -12,12 +12,12 @@ import { useI18n } from "@/lib/i18n";
 import { springGentle } from "@/lib/motion";
 import { UNORGANIZED_ID, type Deck } from "@/lib/schemas";
 import { shareDeck } from "@/lib/share";
-import { appendActivities, deleteDeck, downloadDeck, renameDeck, upsertDeck } from "@/lib/storage";
+import { appendActivities, deleteDeck, deleteNotesText, downloadDeck, renameDeck, upsertDeck } from "@/lib/storage";
 import { showToast } from "@/lib/toast";
 import { useBackClose } from "@/lib/use-back-close";
 import { useIsPhone } from "@/lib/use-phone";
 import { cn, formatDate, truncate } from "@/lib/utils";
-import { ChevronDownIcon, DownloadIcon, EllipsisIcon, FolderIcon, PlayIcon, RefreshIcon, ShareIcon } from "@/components/icons";
+import { ChatIcon, ChevronDownIcon, DownloadIcon, EllipsisIcon, FolderIcon, PlayIcon, RefreshIcon, ShareIcon, XCircleIcon } from "@/components/icons";
 import { Button, ProgressBar } from "@/components/ui";
 
 type Busy = null | "more" | "regenerate";
@@ -378,6 +378,13 @@ export function DeckCard({
             <ShareIcon className="size-4 text-[var(--text-subtle)]" />
             {t("deck.share")}
           </button>
+          <Link
+            href={`/chat?deck=${deck.id}`}
+            className={menuRow}
+          >
+            <ChatIcon className="size-4 text-[var(--text-subtle)]" />
+            {t("chat.askAboutDeck")}
+          </Link>
           <button
             type="button"
             className={menuRow}
@@ -388,6 +395,21 @@ export function DeckCard({
             {t("deck.regenerate")}
           </button>
 
+          {hasSource ? (
+            <button
+              type="button"
+              className={menuRow}
+              onClick={() => {
+                setMenuOpen(false);
+                deleteNotesText(deck.id);
+                showToast({ message: t("chat.notesDeleted") });
+              }}
+            >
+              <XCircleIcon className="size-4 text-[var(--text-subtle)]" />
+              {t("chat.deleteNotes")}
+            </button>
+          ) : null}
+
           {/* Deleting is reversible: no confirm, just an Undo toast. */}
           <button
             type="button"