perf(chat): isolate the composer, split heavy chunks, fix dead tokens

Second batch from the staging UX audit (BUG-248..253).

- css: expose the 32 palette tokens through @theme. Seven utilities
  including text-ink, text-danger and text-warning compiled to no CSS
  at all, so 30 call sites had been silently inert (BUG-248)
- chat: move the composer into its own component behind a draft store,
  so a keystroke no longer re-renders a 2723-line component, and
  persist the draft across reloads (BUG-249)
- chat: load gsap, react-markdown and thinking-orbs on demand. First
  Load JS for / drops 549.5 kB to 476.3 kB gzipped (BUG-250)
- chat: route the five in-app destinations through router.push, and
  keep the five auth redirects and the bootstrap retry as hard loads
  on purpose (BUG-251)
- a11y: announce reply completion, and move the live region out of the
  aria-busy subtree that was likely suppressing even the start
  announcement (BUG-252)
- docs: give the 27 collided bug ids unique numbers and repair their
  inbound references; require search rather than a full read of a
  3690-line file (BUG-253)

Verified: tsc, eslint, next build, and 1592 assertions across the 199
non-database test files.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/lib/chat-reply-announcement.ts

@@ -0,0 +1,32 @@
+export type ChatReplyPhase =
+  | "idle"
+  | "generating"
+  | "recovering"
+  | "completed"
+  | "stopped"
+  | "failed";
+
+export type ChatReplyAnnouncer =
+  | "none"
+  | "reply_status_region"
+  | "chat_notice_toast"
+  | "conversation_alert";
+
+const announcers = {
+  idle: "none",
+  generating: "reply_status_region",
+  recovering: "chat_notice_toast",
+  completed: "reply_status_region",
+  stopped: "chat_notice_toast",
+  failed: "conversation_alert",
+} as const satisfies Record<ChatReplyPhase, ChatReplyAnnouncer>;
+
+export function chatReplyAnnouncer(phase: ChatReplyPhase): ChatReplyAnnouncer {
+  return announcers[phase];
+}
+
+export function chatReplyAnnouncement(phase: ChatReplyPhase, replyOrdinal: number): string {
+  if (chatReplyAnnouncer(phase) !== "reply_status_region") return "";
+  if (phase === "generating") return "Jyotisha 正在回答，完成后会提示你阅读。";
+  return `Jyotisha 已回答完毕，第 ${replyOrdinal} 条回答已显示在对话区末尾，可以开始阅读。`;
+}

frontend/src/lib/composer-draft.ts

@@ -0,0 +1,105 @@
+export const composerDraftStorageKey = "jyotisha.composer-draft";
+
+const composerDraftLimit = 500;
+const composerDraftMaxAgeMs = 24 * 60 * 60 * 1000;
+
+const listeners = new Set<() => void>();
+
+let draft = "";
+let restored = false;
+
+function draftStorage(): Storage | null {
+  if (typeof window === "undefined") return null;
+  try {
+    return window.sessionStorage;
+  } catch {
+    // Private-mode browsers without session storage keep the draft in memory only.
+    return null;
+  }
+}
+
+function clearStoredDraft() {
+  const storage = draftStorage();
+  if (!storage) return;
+  try {
+    storage.removeItem(composerDraftStorageKey);
+  } catch {
+    // A rejected write never blocks the composer.
+  }
+}
+
+export function readStoredComposerDraft(): string {
+  const storage = draftStorage();
+  if (!storage) return "";
+  let stored: string | null = null;
+  try {
+    stored = storage.getItem(composerDraftStorageKey);
+  } catch {
+    return "";
+  }
+  if (!stored) return "";
+  try {
+    const parsed = JSON.parse(stored) as Record<string, unknown>;
+    const text = parsed.text;
+    const savedAt = parsed.savedAt;
+    if (typeof text !== "string"
+      || typeof savedAt !== "number"
+      || !Number.isFinite(savedAt)
+      || savedAt > Date.now()
+      || Date.now() - savedAt > composerDraftMaxAgeMs) {
+      clearStoredDraft();
+      return "";
+    }
+    return text.slice(0, composerDraftLimit);
+  } catch {
+    clearStoredDraft();
+    return "";
+  }
+}
+
+function writeStoredComposerDraft(value: string) {
+  if (!value) {
+    clearStoredDraft();
+    return;
+  }
+  const storage = draftStorage();
+  if (!storage) return;
+  try {
+    storage.setItem(composerDraftStorageKey, JSON.stringify({
+      text: value.slice(0, composerDraftLimit),
+      savedAt: Date.now(),
+    }));
+  } catch {
+    // A full or blocked storage never blocks typing.
+  }
+}
+
+function restoreComposerDraft() {
+  if (restored) return;
+  restored = true;
+  draft = readStoredComposerDraft();
+}
+
+export function composerDraftSnapshot(): string {
+  restoreComposerDraft();
+  return draft;
+}
+
+export function serverComposerDraftSnapshot(): string {
+  return "";
+}
+
+export function setComposerDraft(value: string) {
+  restoreComposerDraft();
+  if (draft === value) return;
+  draft = value;
+  writeStoredComposerDraft(value);
+  for (const listener of [...listeners]) listener();
+}
+
+export function subscribeComposerDraft(listener: () => void): () => void {
+  listeners.add(listener);
+  return () => {
+    listeners.delete(listener);
+  };
+}