ui: consistency sweep — the 1ch rail geometry, Submit thinking, no auto-caps

Owner round 4 (2026-10-05):

- THE RAIL IS THE MISSING CHARACTER: rail + padding = exactly 1ch of
  the mono heading font. 'YOUR THINKING' (13ch) + rail == 'AGENT
  THINKING' (14ch) flush — the chevrons line up vertically, no fixed
  columns. The YOU heading joins the rail (label inside, like the
  thinking rows) — one quote geometry everywhere.
- HEADING REGISTER: YOUR THINKING / AGENT THINKING / YOU all use the
  card eyebrows' small mono caps (text-xs = the 11px rung, font-medium
  uppercase tracking-wide) — the app chrome is JetBrains Mono.
- SUBMIT THINKING: the practice button is now literally the question
  dock's Button (h-9, px-3.5) in one p-1 row with the hint left
  ('↵ submits · ⇧↵ newline') — the keyboard hints are back. Corner
  radii concentric in both docks: shell 16 − 6 = field 10 − 4 = button 6
  (rounded-[10px] fields, rounded-[6px] buttons — the old rounded-xl/12
  was the 'too large' culprit).
- MODEL NAMES: prettyModel no longer auto-capitalizes — names render
  exactly as their providers write them ('glm 5.3 flash').
- Quiz explanations pulled closer (mt-3 → mt-2).

components/usage-format.ts

@@ -39,6 +39,8 @@ export function prettyModel(id: string, qualified = false): string {
 	const short = bare.includes("/") ? bare.slice(bare.lastIndexOf("/") + 1) : bare;
 	const parts = short.split("-");
 	const trimmed = /^\d+$/.test(parts[parts.length - 1] ?? "") ? parts.slice(0, -1) : parts;
-	const pretty = trimmed.map((p) => p.charAt(0).toUpperCase() + p.slice(1)).join(" ");
+	// No auto-capitalization (owner round 4, 2026-10-05): model names
+	// render exactly as their providers write them.
+	const pretty = trimmed.join(" ");
 	return qualified && provider ? `${pretty} · ${provider}` : pretty;
 }