v0.7.6 — the solitaire door could not reach solitaire

Found by Jesse playing v0.7.5 on phoenix.local: a browser that had ever
held a multiplayer seat could not reach the new solitaire setup screen
at all. start() checked a browser-remembered multiplayer session before
ever looking at solitaire's own state, and a bare ./play.html load could
not tell "clicked Play solitaire" apart from "reloaded mid multiplayer
game" — the same problem ?lobby already solved for the door on the
other side, never applied to this one.

The door now links to ./play.html?solitaire, and start() treats that,
an explicit ?seed=, or the setup screen's own ?hand= (written by every
Deal) as proof this navigation means solitaire — checked ahead of the
remembered-session lookup rather than only below it.

862 tests pass, three new.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AdG46Ja2PEDBkpqiDazMoX

package.json

@@ -1,6 +1,6 @@
 {
   "name": "station-master",
-  "version": "0.7.5",
+  "version": "0.7.6",
   "private": true,
   "type": "module",
   "description": "Station Master — a railroad operations game",