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/practice-dock.tsx

@@ -3,6 +3,7 @@
 import { useCallback, useRef, useState } from "react";
 import { ChevronRightIcon } from "lucide-react";
 import { MessageResponse } from "@/components/ai-elements/message";
+import { Button } from "@/components/ui/button";
 import { joinDictation, useDictationTarget } from "@/components/dictation";
 import { cn } from "@/lib/utils";
 
@@ -102,7 +103,7 @@ export function PracticeDock({ problemCallId, input, expanded, onExpand, onSubmi
 			    Shift+Enter makes a newline — less to decide about. */}
 			<div
 				data-testid="practice-thinking-field"
-				className="m-1.5 rounded-xl border border-border/70 bg-background/60 transition-colors focus-within:border-primary/50"
+				className="m-1.5 rounded-[10px] border border-border/70 bg-background/60 transition-colors focus-within:border-primary/50"
 			>
 				<div className="px-2.5 pt-2 text-xs font-medium uppercase tracking-wide text-muted-foreground">
 					YOUR THINKING
@@ -135,18 +136,23 @@ export function PracticeDock({ problemCallId, input, expanded, onExpand, onSubmi
 						"field-sizing-content lh-input max-h-64 min-h-16 w-full resize-none bg-transparent px-2.5 pb-2 outline-none placeholder:text-muted-foreground",
 					)}
 				/>
-				{/* The one Send — docked inside the field like the composer's,
-				    right-aligned. */}
-				<div className="flex items-center justify-end px-1.5 pb-1.5">
-					<button
+				{/* The submit row (owner round 4, 2026-10-05): IDENTICAL to the
+				    question dock's — hint left, the SAME Button (h-9, px-3.5),
+				    one p-1 row. Corner radii concentric: shell 16 − m-1.5 (6) =
+				    field 10 − p-1 (4) = button 6. */}
+				<div className="flex items-center justify-between gap-2 p-1">
+					<span aria-hidden className="pl-1.5 text-xs text-muted-foreground">
+						↵ submits · ⇧↵ newline
+					</span>
+					<Button
 						type="button"
 						data-testid="practice-send"
 						disabled={thinking.trim().length === 0}
 						onClick={() => submit()}
-						className="rounded-lg bg-primary px-3 py-1.5 text-sm font-medium text-primary-foreground transition-colors hover:bg-primary/90 disabled:pointer-events-none disabled:opacity-40"
+						className="ml-auto h-9 rounded-[6px] px-3.5 text-sm font-medium"
 					>
-						Send
-					</button>
+						Submit thinking
+					</Button>
 				</div>
 			</div>
 		</div>