v0.4.9e — five of six playtest bugs: one button per train, and a load that has to go somewhere

Gameplay testing on 0.4.9d returned six reports. Five are fixed; the sixth could not be
reproduced and is written up in TODO.md with the two questions that would pin it down.

TWO TRAINS AT ONE PLATFORM ANSWERED TO ONE BUTTON. `porter.board` and `porter.detrain`
carried no tray, so there was one button per platform however many trains stood at it and
the reducer filled the first empty coach on the A/D tracks. `check` and the reducer were not
even asking the same question: `check` skipped a train whose card refuses passenger work and
the reducer did not. Both intents now carry an optional `trayId`, one function resolves the
train and the coach for check/execute/reduce alike, `legal.ts` offers one candidate per train,
and the label names it.

A LOAD COULD BE MADE AND BROKEN WITHOUT GOING ANYWHERE. A Freight House could unload the
boxcar it had just loaded; a platform could detrain the passengers it had just boarded. Full
Revenue at both ends for a movement that never happened. Jesse's rule: a load made anywhere in
an Office Area may not be broken anywhere in that Office Area, ever — it has to be carried to
another district. The load carries the seat that made it (`RollingStock.origin`), stripped by
`pooled` at every yard push. Measured at -0.60 +/- 0.10 Revenue a game (t = -6.1) over 400
paired deals: 78 worse, 3 better, 319 unchanged — free Revenue coming off the board, not a nerf.

THE GROCER'S WAREHOUSE SHIPPED AND THE REFINERY RECEIVED. Both were `flow: 'both'` on the
reading that "Freight House" was a collective term for exactly those two, and therefore what
§9.3 described. The engine has dealt a Freight House CARD since before v0.4.9, so §9.3 names
it and the argument goes. The card set agrees: all three Refinery modifiers grant +1 outbound.
Refinery outbound-only, Grocer's inbound-only, Freight House the one two-way industry — which
leaves exactly the one same-district pairing the rule above refuses.

NOT REPRODUCED: cars left behind when backing up over them. Five layouts tried, including cars
spotted at an industry; every one couples the lot. Three are pinned in `apply.test.ts`. One way
to create such cars was closed anyway — `flyingSwitch` wrote its cut past `carsOn`.

Both published replays that had gone dead were re-recorded; a rules change retires a save, and
`harness.test.ts` is what catches it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011nbvwWMef8CuEP6t5cgkTv

public/replays/seed-927523.json

@@ -1,7 +1,7 @@
 {
  "seed": 927523,
- "title": "12 Revenue · seed 927523",
- "note": "12 Revenue over 5 Days · 2 train(s) on the timetable · 20 cards down · no collisions · played by developer",
+ "title": "11 Revenue · seed 927523",
+ "note": "11 Revenue over 5 Days · 2 train(s) on the timetable · 21 cards down · no collisions · played by developer",
  "rules": {
   "startingHand": "threeRandom",
   "revenue": {
@@ -320,21 +320,24 @@
    "at": {
     "row": 0,
     "col": 0
-   }
+   },
+   "trayId": "tray3"
   },
   {
    "type": "porter.board",
    "at": {
     "row": 0,
     "col": 0
-   }
+   },
+   "trayId": "tray3"
   },
   {
    "type": "porter.detrain",
    "at": {
     "row": 0,
     "col": 0
-   }
+   },
+   "trayId": "tray3"
   },
   {
    "type": "loadUnload.end"
@@ -589,21 +592,24 @@
    "at": {
     "row": 0,
     "col": 0
-   }
+   },
+   "trayId": "tray2"
   },
   {
    "type": "porter.board",
    "at": {
     "row": 0,
     "col": 0
-   }
+   },
+   "trayId": "tray2"
   },
   {
    "type": "porter.detrain",
    "at": {
     "row": 0,
     "col": 0
-   }
+   },
+   "trayId": "tray2"
   },
   {
    "type": "loadUnload.end"
@@ -951,36 +957,38 @@
    "at": {
     "row": 0,
     "col": 0
-   }
+   },
+   "trayId": "tray3"
   },
   {
    "type": "porter.board",
    "at": {
     "row": 0,
     "col": 0
-   }
-  },
-  {
-   "type": "porter.detrain",
-   "at": {
-    "row": 0,
-    "col": 0
-   }
+   },
+   "trayId": "tray3"
   },
   {
    "type": "loadUnload.end"
   },
   {
    "type": "localOps.choose",
-   "option": "freightAgent"
+   "option": "draw"
   },
   {
-   "type": "freightAgent.clearInbound",
-   "at": {
-    "row": 0,
-    "col": 0
+   "type": "draw.fromHomeOffice"
+  },
+  {
+   "type": "card.play",
+   "cardId": "c162",
+   "placement": {
+    "row": -2,
+    "col": 2
    },
-   "index": 0
+   "variant": 1
+  },
+  {
+   "type": "draw.end"
   },
   {
    "type": "loadUnload.end"
@@ -1179,6 +1187,12 @@
    "carType": "coach",
    "loaded": false
   },
+  {
+   "type": "newTrain.placeCar",
+   "trayId": "tray3",
+   "carType": "coach",
+   "loaded": false
+  },
   {
    "type": "laborer.advanceLoad",
    "at": {
@@ -1236,7 +1250,58 @@
    "option": "switch"
   },
   {
-   "type": "switch.end"
+   "type": "switch.move",
+   "trayId": "tray3",
+   "to": {
+    "row": 0,
+    "col": 1
+   },
+   "reverse": true
+  },
+  {
+   "type": "switch.move",
+   "trayId": "tray3",
+   "to": {
+    "row": 0,
+    "col": 0
+   },
+   "reverse": false
+  },
+  {
+   "type": "switch.move",
+   "trayId": "tray3",
+   "to": {
+    "row": 0,
+    "col": 1
+   },
+   "reverse": true
+  },
+  {
+   "type": "switch.move",
+   "trayId": "tray3",
+   "to": {
+    "row": 0,
+    "col": 0
+   },
+   "reverse": false
+  },
+  {
+   "type": "switch.move",
+   "trayId": "tray3",
+   "to": {
+    "row": 0,
+    "col": 1
+   },
+   "reverse": true
+  },
+  {
+   "type": "switch.move",
+   "trayId": "tray3",
+   "to": {
+    "row": 0,
+    "col": 0
+   },
+   "reverse": false
   },
   {
    "type": "laborer.advanceLoad",