Chat chrome docks into the rail; drop the notes-off banner

The chat header and composer are full-bleed bands inside the main
pane, which starts right at the sidebar on desktop - so both ended in
a hard vertical edge beside the floating rail card (the 12px gutter
showed the raw scene and the bands' fill + backdrop blur read as a
color step at the seam), with their hairlines starting in mid-air at
that edge. Both bands now reach the card's right edge (the rail's own
12px padding, expanded or collapsed) and their hairlines are inset to
the content box; phones keep the plain full-width borders. The chat
suite pins the dock. The "Chat is set to ignore notes text" banner
went away - the scope chip already says what the chat may read.

Version 0.5.5, SW -> freezmo-v77. Chat 104/104 (2 new), mobile
126/126, wizard 95/95, phase3 31/31, bubbles 34/34, i18n 13/13,
native 33/33, regression 44/44, contrast 0 findings, axe clean.
Full e2e: 14/14 suites.

components/chat/ChatScreen.tsx

@@ -3,7 +3,6 @@
 import { useCallback, useEffect, useMemo, useRef, useState, useSyncExternalStore } from "react";
 import { useRouter, useSearchParams } from "next/navigation";
 import { useAppReducedMotion as useReducedMotion } from "@/lib/motion-pref";
-import Link from "next/link";
 
 import { Composer, type PendingAttachment } from "./Composer";
 import { ContextPicker } from "./ContextPicker";
@@ -769,14 +768,6 @@ export function ChatScreen() {
         />
       </div>
 
-      {settings.chatNotes === false && scope.kind !== "none" ? (
-        <p className="border-t border-[var(--hairline-soft)] bg-[var(--surface-sunken)] px-4 py-2 text-[11.5px] text-[var(--text-subtle)]">
-          {t("chat.notesOffNote")}{" "}
-          <Link href="/" className="underline decoration-dotted">
-            {t("chat.notesOffLink")}
-          </Link>
-        </p>
-      ) : null}
       </div>
 
       <HistorySheet