feat(games): draft Valheim

Drafted and boot-tested by the GBR builder (job 4b174b2d-48ad-455d-b979-6c36e2b0ce9f).

games/valheim/test.yaml

@@ -0,0 +1,6 @@
+# yaml-language-server: $schema=../../schema/test.schema.json
+# Values CI uses to boot-test this game. Never put real credentials here: map them under 'secrets'.
+config: {}
+readyExample: '10/25/2026 21:27:59: Loading: Done. Total seconds sinze ZNet start: 36.851581, Genloc duration: 29122.732 ms, (Total genloc time: 00:00:29.3234120, locations: 183, iterations: 0)'
+secrets: {}
+timeoutSec: 2400