test: prove unrelated project isolation

tests/fixtures/awesome-ski-game/handbook/proof/playtest.toml

@@ -0,0 +1,11 @@
+[[nodes]]
+schema_version = 1
+id = "proof.carve-playtest"
+title = "Carve playtest proof"
+family = "proof"
+authority = "derived"
+status = "verified"
+tags = ["carving", "playtest", "proof"]
+summary = "Records that the edge-control fixture has a bounded test target."
+content = "The test target records grip, carve angle, skid state, and the route segment for each sample."
+proves = ["riding.edge-control"]

tests/fixtures/awesome-ski-game/handbook/riding/edge-control.md

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++++
+schema_version = 1
+id = "riding.edge-control"
+title = "Edge control"
+family = "riding"
+authority = "approved_plan"
+status = "ready"
+tags = ["carving", "controls", "snow"]
+summary = "Defines how player input produces grip, carve angle, and controlled skidding."
+depends_on = ["trail.glacier-bowl"]
++++
+
+Edge input changes ski grip continuously. Higher edge angles create tighter carved turns when the
+surface supports them; excessive angle or poor snow contact produces a controlled skid.

tests/fixtures/awesome-ski-game/handbook/safety/avalanche-window.md

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++++
+schema_version = 1
+id = "safety.avalanche-window"
+title = "Avalanche window"
+family = "safety"
+authority = "authoritative"
+status = "current"
+tags = ["conditions", "risk", "weather"]
+summary = "Defines the conditions that close exposed terrain during the test session."
+informs = ["session.first-descent"]
++++
+
+The session closes exposed terrain when wind loading crosses the configured safety threshold. A
+closure changes route availability but does not rewrite the terrain definition.

tests/fixtures/awesome-ski-game/handbook/session/first-descent.md

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++++
+schema_version = 1
+id = "session.first-descent"
+title = "First descent session"
+family = "session"
+authority = "approved_plan"
+status = "active"
+tags = ["playtest", "route", "session"]
+summary = "Combines one route, one riding mechanic, and current safety conditions for a playtest."
+depends_on = ["riding.edge-control", "safety.avalanche-window", "trail.glacier-bowl"]
++++
+
+The first descent starts on the sheltered practice face, crosses the bowl, and exits through the
+marked lower route. The session records completion time, falls, controlled skids, and route closure.

tests/fixtures/awesome-ski-game/handbook/trails/glacier-bowl.md

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++++
+schema_version = 1
+id = "trail.glacier-bowl"
+title = "Glacier Bowl"
+family = "trail"
+authority = "authoritative"
+status = "open"
+tags = ["alpine", "route", "snow"]
+summary = "Defines the terrain and route constraints for the first playable descent."
++++
+
+Glacier Bowl is a wide alpine route with one narrow entry, a sheltered practice face, and a marked
+exit. The playable route must keep the entry and exit readable in flat light.