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.

lib/chat.ts

@@ -1,53 +1,17 @@
 "use client";
 
 /**
- * Chat types shared by the chat UI, the context builder and the streaming
- * client. The API key rule applies here too: nothing in a chat request may
- * carry the key anywhere except the `x-ollama-key` header of our own route.
+ * Chat helpers and types shared by the chat UI. The record shapes themselves
+ * live in `lib/schemas.ts` (zod, shared with backup/sync); this module
+ * re-exports them so UI code has one import.
  */
 
-export type ChatRole = "user" | "assistant";
+import type { ChatAttachment, ChatMessage, ChatScope, ChatSource } from "./schemas";
 
-/** A context chunk that actually travelled with a request. */
-export type ChatSource = {
-  deckId: string;
-  deckTitle: string;
-  section: string;
-};
-
-export type ChatAttachment = {
-  name: string;
-  kind: "photo" | "document" | "text";
-  chars: number;
-};
+export type { ChatAttachment, ChatMessage, ChatScope, ChatSource };
 
 export type ChatError = { message: string; kind?: string };
 
-export type ChatMessage = {
-  id: string;
-  role: ChatRole;
-  content: string;
-  /** Reasoning streamed separately; hidden behind the Thinking row. */
-  thinking?: string;
-  /** Model that produced an assistant turn. */
-  model?: string;
-  /** Context chunks sent with this turn (assistant turns display them). */
-  sources?: ChatSource[];
-  attachments?: ChatAttachment[];
-  at: number;
-  /** Set when an assistant turn failed; content may hold a partial answer. */
-  error?: ChatError;
-};
-
-/**
- * What the chat is allowed to ground on. `all` = every deck with notes,
- * `none` = general chat, `decks` = a chosen set.
- */
-export type ChatScope =
-  | { kind: "all" }
-  | { kind: "none" }
-  | { kind: "decks"; deckIds: string[] };
-
 export type ChatModelChoice = {
   name: string;
   badge: "text" | "vision" | "both";
@@ -81,3 +45,28 @@ export function chatMessageId(prefix: string): string {
       : Math.random().toString(36).slice(2, 10);
   return `${prefix}_${Date.now().toString(36)}_${rand}`;
 }
+
+/** Auto title from the first user turn (markdown stripped, one line). */
+export function titleFromMessage(content: string): string {
+  const line = content
+    .replace(/[#*`>_]/g, "")
+    .replace(/\s+/g, " ")
+    .trim();
+  if (!line) return "";
+  return line.length > 60 ? `${line.slice(0, 57)}…` : line;
+}
+
+/** Case/diacritic-insensitive search over titles and message text. */
+export function conversationMatches(title: string, messages: ChatMessage[], query: string): boolean {
+  const needle = fold(query);
+  if (!needle) return true;
+  if (fold(title).includes(needle)) return true;
+  return messages.some((message) => fold(message.content).includes(needle));
+}
+
+function fold(value: string): string {
+  return value
+    .toLowerCase()
+    .normalize("NFKD")
+    .replace(/[\u0300-\u036f]/g, "");
+}