ui: round three — the tight band, one geometry everywhere

Owner round three on the user rows: (1) the band padding halves,
py-2.5 -> py-[5px] — subtle, not tall; same for the messages. (2) The
in-card thinking joins the band: identical styling and heights for
collapsed thinking in the chat and inside question cards (card-on-card
is quiet by design; revert if it reads too light). (3) The left gap
MATCHES the new 5px padding, so the rail fills the rest of the 3ch
inset - border-l-[calc(3ch-5px)] pl-[5px]: a thick muted rail, total
inset still 3ch (the chevron-alignment law survives). The banded prop
dies - one geometry, cards included.

components/answered-card.tsx

@@ -143,16 +143,11 @@ export function AnsweredCard({ answer }: { answer: QuestionAnswerData }) {
 
 			{(answer.thinking ?? answer.note) && (
 				/* The SAME unified row (owner round, 2026-10-05): the quiz answer's
-				    thinking is the identical collapsible ThinkingBlock — it just
-				    happens to sit INSIDE the card, so it takes the rail but no band
-				    (owner round two, 2026-10-07: card-color on card-color would be
-				    invisible; geometry alone carries it there). */
-				<ThinkingBlock
-					testId="your-thinking"
-					label="YOUR THINKING"
-					text={answer.thinking ?? answer.note ?? ""}
-					banded={false}
-				/>
+				    thinking is the identical collapsible ThinkingBlock — and since
+				    owner round three (2026-10-07) IDENTICALLY styled, band and all:
+				    collapsed thinking matches in height everywhere, card or chat
+				    (card-on-card is quiet by design; too light → revert). */
+				<ThinkingBlock testId="your-thinking" label="YOUR THINKING" text={answer.thinking ?? answer.note ?? ""} />
 			)}
 
 			{/* px-3→removed: card p-4 + box px-3 double-inset sat the "Why" label deeper