v0.4.9d — three playtest bugs: a train that looked gone, an unload that ignored the pick, a hang that wasn't one

Patched directly onto 0.4.9a rather than the in-progress 0.5.0 line.

A switching train vanished from the board the moment it left the Office. `selectedTrain` in
`officeSvg` (board-svg.ts), which gates whether a card draws a train's crew badge, was only ever
assigned inside the `cell.adTracks !== null` branch — true for the Office card alone. A train
standing anywhere else, which is everywhere it stands while actually being switched, drew no badge
at all. Game state was never affected; confirmed against the reported save with the engine directly.
Fix hoists the assignment out of the guard so it runs for any card with a train on it.

Unloading always took the westmost car, whichever one was picked. `laborer.beginUnload` carried the
player's chosen `carIndex`, and `check()` validated that specific car, but the `unloadBegan` event
it produced carried only the car's type — the reducer that performs the swap re-derived the target
with `industryTrack.cars.findIndex(c => c.loaded)`, which always answers the first loaded car in
track order regardless of what was requested. Fix adds `carIndex` to the event and uses it directly.

A legal decision could render with zero buttons, which looked exactly like a hang. The "where does
this Extra start" decision is titled by `trainCardTitle`, beginning "Making up Extra X22…" — the
same prefix `renderActions()` stripped from the action list on the assumption it only ever belonged
to the separate yard-chip car-placement panel. With no tray yet being filled, that panel is null, so
nothing rendered the Extra's decision either: a legal, correctly-computed option with no button
anywhere on the page. Replaying the reported save found no engine deadlock at any step — the engine
always had a move. Fix matches the exact title of the one group the yard-chip panel covers instead
of a title-prefix regex.

New tests for all three: a train parked on an ordinary facility card must draw its crew badge; three
differently-typed loaded cars, unloading index 2, must leave indices 0 and 1 alone; the existing
softlock regression test now mirrors the real render filter instead of only the raw menu, plus a
deterministic test for the exact reported scenario. 590 tests, 0 failures.

src/engine/apply.ts

@@ -1663,7 +1663,13 @@ function execute(s: GameState, player: PlayerIndex, i: Intent): GameEvent[] {
     case 'laborer.beginUnload': {
       const f = facilityAt(s, player, i.at)!;
       return [
-        { type: 'unloadBegan', player, at: i.at, carType: f.industryTrack.cars[i.carIndex]!.type },
+        {
+          type: 'unloadBegan',
+          player,
+          at: i.at,
+          carType: f.industryTrack.cars[i.carIndex]!.type,
+          carIndex: i.carIndex,
+        },
       ];
     }
 
@@ -2206,7 +2212,17 @@ export function reduce(s: GameState, e: GameEvent): void {
 
     case 'unloadBegan': {
       const f = facilityAt(s, e.player, e.at)!;
-      const ci = f.industryTrack.cars.findIndex((c) => c.loaded);
+      /**
+       * THE CAR THE PLAYER PICKED, not merely "a loaded one".
+       *
+       * REPORTED: with several loaded cars spotted on one industry track, unloading always took the
+       * WESTMOST car regardless of which one was chosen. This used to re-derive the target with
+       * `industryTrack.cars.findIndex(c => c.loaded)`, which returns the same answer — the first
+       * loaded car in track order — no matter which `carIndex` the intent actually named; `check`
+       * had already validated that specific car, and the choice was thrown away between there and
+       * here. `e.carIndex` is exactly what `laborer.beginUnload`'s reducer read off the intent.
+       */
+      const ci = e.carIndex;
       if (ci >= 0) {
         /**
          * §9.3 — the replacement empty comes out of the Division Yard. Conjuring it here is what