Initial public release of PSX Adventure Engine

Browser reference stack for PSX-era third-person adventure: fixed cameras,
inventory puzzles, Box3D physics, host-authoritative P2P co-op, and a modular
character harness. Ships the Ashgrove Precinct Level 1 investigation demo with
a full cast and nine linked rooms.

.env.example

@@ -0,0 +1,9 @@
+# Optional server overrides (copy to server/.env or export in shell)
+# PORT=8787
+# PSX_SESSION_SECRET=replace-with-a-long-random-string
+
+# Optional client (defaults to local server)
+# VITE_API_URL=http://localhost:8787
+
+# Optional tools — path to the Grok CLI if not on PATH
+# GROK_BIN=grok