fix(ui): give the rail its own short labels instead of the sheet's sentences

The corner rail rendered `Shortcut.meaning`, which is written for the `?` sheet
where a full sentence is exactly right because somebody is reading a reference.
The rail is a glance over a moving 3D board with room for one line, and it is a
`flex-wrap` container: the sentence wrapped, and the wrapped line drew straight
through the chip beneath it. On the deployed build "Fly to a chapter of the tour,
or to a viewpoint inside a studio" and "Walk into the studio, or step back out to
the city" overlapped and neither could be read, over a bright sky with no
background to hide it. Nothing errored — it just looked broken, on every screen.

Two labels for two jobs. `Shortcut.rail` carries the two-or-three-word form for
the nine ids `railHints` can select; `meaning` keeps the sentence for the sheet.

`.hint` also had no `line-height`, so it inherited the body's and a wrapped chip
had nowhere to go, and no `max-width`, so the rail grew leftward until it met the
mode pill. Chips are now `white-space: nowrap`: wrapping belongs between chips,
which the flex container already does, not inside one.

Tested, because this is a defect a test can hold: every id the rail can return
must have a `rail` label, it must fit on a line, and it must not contain a
clause.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/ui/chromeState.ts

@@ -565,7 +565,10 @@ export function chromeState(inputs: ChromeInputs): ChromeState {
   const hints = railHints(mode, touchFirst).map((entry) => ({
     id: entry.id,
     keys: entry.keys,
-    label: entry.meaning,
+    // `rail`, not `meaning`: the sheet gets the sentence, the rail gets the
+    // glance. See the field's note in `shortcuts.ts` for what reusing the
+    // sentence here actually looked like on screen.
+    label: entry.rail ?? entry.meaning,
   }));
 
   // ---- The honesty line ---------------------------------------------------

src/ui/shortcuts.ts

@@ -95,6 +95,21 @@ export interface Shortcut {
   gesture?: string;
   /** What it does, in one clause, true in every mode the scope admits. */
   meaning: string;
+  /**
+   * The two-or-three-word form, for the rail in the corner of the scene.
+   *
+   * `meaning` is written for the `?` sheet, where a full sentence is exactly
+   * right — it is a reference somebody is reading. The rail is a glance over a
+   * moving 3D board with room for one line, and reusing the sentence there put
+   * "Fly to a chapter of the tour, or to a viewpoint inside a studio" in a
+   * flex-wrap container: it wrapped, the wrapped line collided with the chip
+   * below it, and both were illegible over a bright sky. Two labels for two
+   * jobs, rather than one label doing neither well.
+   *
+   * Optional: a shortcut the rail never selects does not need one, and
+   * `railHints` only ever picks from a fixed set of ids.
+   */
+  rail?: string;
   section: ShortcutSection;
   scope: ShortcutScope;
   /**
@@ -128,6 +143,7 @@ export const KEYMAP: readonly Shortcut[] = [
     id: "move",
     keys: ["W", "A", "S", "D"],
     meaning: "Move: drive, walk, or fly whatever you are controlling",
+    rail: "Move",
     section: "move",
     scope: "play",
     control: "forward",
@@ -142,6 +158,7 @@ export const KEYMAP: readonly Shortcut[] = [
      * in one of the four modes it fires in.
      */
     meaning: "The primary action of whatever you are controlling — sprint, handbrake, throttle, climb",
+    rail: "Boost",
     section: "move",
     scope: "play",
     control: "primary",
@@ -151,6 +168,7 @@ export const KEYMAP: readonly Shortcut[] = [
     id: "altitude",
     keys: ["Q", "E"],
     meaning: "Descend / climb, flying as a crow or an aircraft",
+    rail: "Altitude",
     section: "move",
     scope: "fly",
     control: "ascend",
@@ -160,6 +178,7 @@ export const KEYMAP: readonly Shortcut[] = [
     id: "pitch",
     keys: ["I", "K"],
     meaning: "Pitch the nose up / down while flying",
+    rail: "Pitch",
     section: "move",
     scope: "fly",
     control: "pitch-up",
@@ -175,6 +194,7 @@ export const KEYMAP: readonly Shortcut[] = [
      */
     keys: ["G"],
     meaning: "Glide — stop beating and hold the air, as a crow",
+    rail: "Glide",
     section: "move",
     scope: "crow",
     control: "secondary",
@@ -184,6 +204,7 @@ export const KEYMAP: readonly Shortcut[] = [
     id: "assist",
     keys: ["P"],
     meaning: "Hand the vehicle or aircraft back to its assisted route",
+    rail: "Autopilot",
     section: "move",
     scope: "drive",
     edge: "assist",
@@ -213,6 +234,7 @@ export const KEYMAP: readonly Shortcut[] = [
     id: "office",
     keys: ["O"],
     meaning: "Walk into the studio, or step back out to the city",
+    rail: "Studio",
     section: "world",
     scope: "always",
     onScreen: "the door button at the top of the left column",
@@ -221,6 +243,7 @@ export const KEYMAP: readonly Shortcut[] = [
     id: "walk",
     keys: ["V"],
     meaning: "Take control of a body — walk inside a studio, explore outside one",
+    rail: "Take control",
     section: "world",
     scope: "always",
     onScreen: "Walk / Explore in the left column, or the mode dock",
@@ -237,6 +260,7 @@ export const KEYMAP: readonly Shortcut[] = [
     id: "chapters",
     keys: ["1", "…", "9"],
     meaning: "Fly to a chapter of the tour, or to a viewpoint inside a studio",
+    rail: "Chapters",
     section: "world",
     scope: "always",
     onScreen: "the numbered list in the left column",