v0.8.0.9 — the bot plans its switching turn, stops wasting its draws, and the engine walks each route once

The developer bot, re-measured decision by decision against the bot before it,
goes from about -0.3 revenue a game to about 4.8:

- plans the whole switching turn before its first Move (sim/switch-planner.ts),
  +2.89 over 1600 paired seeds; closes TODO #53
- takes a face-up card only if it could play it, +1.52 over 1600 seeds
- stops running Second Sections by accident in the New Train phase, +0.32
- lays track by what the district can do afterwards, +0.12 over 6400 seeds,
  run-arounds in 22 of 60 districts against 9

The engine is 2.8x faster with play proven identical: a route cache scoped to
one unchanged position, applyIntent split into prepareIntent + commitEvents,
and less allocation in exploreMoves. npm test now leaves out the bot
simulations, which run as npm run test:sim.

No rule changed; games in progress resume. Rejected candidates and the
Second Section card question are in CHANGELOG.md and TODO.md (#104-#106).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017nnuCv8UodHucFfx3LWEoX

src/engine/advance.ts

@@ -522,8 +522,11 @@ type MoveOutcome = 'moved' | 'held' | 'needsClearance';
  *
  * This is reachable purely through switching. A train arrives made up, and only comes apart because
  * the player took cars onto the nose or picked up a cut in a run-around.
+ *
+ * Exported for the switching planner (`sim/switch-planner.ts`), which has to know whether a plan
+ * leaves a train unable to run — and must ask this rule rather than keep a copy of it.
  */
-function badlyMadeUp(tray: CrewTray): string | null {
+export function badlyMadeUp(tray: CrewTray): string | null {
   const n = tray.consist.length;
   if (n === 0) return null;
   const pulling = tray.engineAt === 0;