v0.4.9 — X,Y coordinates, no-switching can still clear the mainline, Q3 corrected, a clearance bug, three sounds, and the box art

A playtest review of seed 58228926 (day 6), plus one long-standing display complaint and the
first real audio beyond a placeholder.

- Coordinate labels read X,Y everywhere shown to a player, not the internal Y,X storage order.
  Display-only.
- "No switching" now means may not add or drop cars, not "never touch it" — these trains can
  still be moved onto Secondary Track to clear the mainline.
- Q3 corrected: Expedite governs WHERE a train may be left standing, not WHEN it leaves. The
  forced same-Stage departure is gone; a new fault costs 1 Revenue if an expedited train is left
  off the station when a Mainline Phase begins. Resolves "3/4 Express prints a rule it can never
  use" as a side effect.
- evaluateClearance now checks every occupant on a Mainline card before offering a judgment
  call, instead of returning on whichever it found first — found while explaining a playtest
  report, fixed with a regression test.
- Three new synthesised sounds: arrive, depart, crash.
- The splash page shows the box art.

Full detail, measurements and reasoning in CHANGELOG.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FvU99NEakShRMg3nN3fHAZ

test/replay.test.ts

@@ -446,6 +446,13 @@ describe('the replay behaves like the game it is replaying', () => {
     assert.ok(kinds.has('couple'), 'coupling a cut never made a sound');
     assert.ok(kinds.has('drop'), 'setting cars out never made a sound');
     assert.ok(kinds.has('schedule'), 'the 1D12 that sets a train\'s departure Stage landed silently');
+    assert.ok(kinds.has('arrive'), 'a train pulling into an Office never made a sound');
+    assert.ok(kinds.has('depart'), 'a train highballing out of an Office never made a sound');
+    // Collisions are rare — measured 2 in 40 games — so this is the one cue this pool is not
+    // guaranteed to contain on every stride; it happens to (seeds 96028 and 159380) at the current
+    // stride and seed count. If this starts failing after either changes, widen the pool rather than
+    // deleting the assertion — §10 is the one event a player most needs to hear.
+    assert.ok(kinds.has('crash'), 'a collision never made a sound');
 
     // One CLOCK cue per Stage boundary, the bell replacing the whistle at a Day — the same
     // accounting the live game is held to. The switching cues are counted separately: they follow