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/Composer.tsx

@@ -70,7 +70,7 @@ export function Composer({
   const canSend = online && !busy && value.trim().length > 0;
 
   return (
-    <div className="border-t border-[var(--glass-border)] bg-[var(--glass-bg)] px-4 pb-safe pt-2 backdrop-blur-xl lg:px-10">
+    <div className="chat-composer-band border-t border-[var(--glass-border)] bg-[var(--glass-bg)] px-4 pb-safe pt-2 backdrop-blur-xl lg:px-10">
       {attachments.length > 0 ? (
         <ul className="mb-2 flex flex-wrap gap-1.5">
           {attachments.map((entry, index) => (