Chat layout: history in the main sidebar, consistent header, cleaner icon

- Desktop: on /chat the main sidebar shows the chat list (search, New chat,
  items with rename/delete, active highlight) in place of the deck
  navigation; the separate second column is gone and the chat uses the full
  width. The expand/collapse chevron sits outside the swappable section and
  a collapsed rail stays clean (the highlighted Chat row already opens a
  new chat). Active conversation travels via a tiny store (lib/chat-active)
  so the sidebar needs no useSearchParams and pages stay static.
- Header (phones): history, theme and New chat are now identical chips -
  same 44px hit area, rounded-2xl, border/surface tokens, size-5 icons,
  even spacing; the title block truncates cleanly. ThemeToggle gained a
  'plain' variant so the header styles it without touching other pages.
- ChatIcon redrawn (clean message-circle, no inner lines) and the empty
  state uses the app's icon-chip pattern (size-12 chip, accent-600/200)
  instead of the bare oversized glyph; the model chip icon follows.
- Also fixed a pre-existing dev-only breakage found while verifying: the
  tab-bar bounce animated three keyframes with a spring, which framer
  motion's dev build throws on - breaking client updates in the dev
  instance (library tab switching, sheet Escape). It now uses a tween.
- Dev metadata keeps the Apple icons in both branches.
- SW -> freezmo-v35.

components/chat/SidebarChatSection.tsx

@@ -0,0 +1,59 @@
+"use client";
+
+import { useRouter } from "next/navigation";
+import { useState, useSyncExternalStore } from "react";
+
+import { ChatHistoryList } from "./HistoryPanel";
+import { chatActive } from "@/lib/chat-active";
+import { chatHistoryStore, deleteConversation, renameConversation, saveConversation } from "@/lib/chat-store";
+import { useI18n } from "@/lib/i18n";
+import { showToast } from "@/lib/toast";
+import type { ChatConversation } from "@/lib/schemas";
+
+/**
+ * Chat history inside the main sidebar: when the Chat section is active the
+ * deck navigation is replaced by the chat list (search, new chat, items with
+ * rename/delete). Collapsed, it keeps one New-chat icon row.
+ */
+export function SidebarChatSection({ collapsed }: { collapsed: boolean }) {
+  const { t } = useI18n();
+  const router = useRouter();
+  const conversations = useSyncExternalStore(
+    chatHistoryStore.subscribe,
+    chatHistoryStore.getSnapshot,
+    chatHistoryStore.getServerSnapshot,
+  );
+  const activeId = useSyncExternalStore(chatActive.subscribe, chatActive.getSnapshot, chatActive.getServerSnapshot);
+  const [query, setQuery] = useState("");
+
+  const onDelete = (conversation: ChatConversation) => {
+    deleteConversation(conversation.id);
+    showToast({
+      message: t("chat.deletedChat"),
+      actionLabel: t("toast.undo"),
+      onAction: () => saveConversation(conversation),
+    });
+  };
+
+  // Collapsed, the list needs width — the highlighted Chat row above (and the
+  // expand chevron) already cover navigation, so the section renders nothing.
+  if (collapsed) return null;
+
+  return (
+    <div className="flex min-h-0 flex-1 flex-col">
+      <h2 className="px-2 pb-1 pt-1 text-[11px] font-semibold uppercase tracking-wider text-[var(--text-subtle)]">
+        {t("chat.history")}
+      </h2>
+      <ChatHistoryList
+        conversations={conversations}
+        currentId={activeId}
+        query={query}
+        onQueryChange={setQuery}
+        onOpen={(id) => router.push(`/chat?c=${id}`)}
+        onRename={renameConversation}
+        onDelete={onDelete}
+        onNew={() => router.push("/chat")}
+      />
+    </div>
+  );
+}