feat(ci): add golden file targets and checklist schema (#486, #497)

Golden targets: make golden-diff shows color diff if simulation output
changed, make golden-update regenerates and stages for review.

Checklist schema: JSON Schema for 7 condition types evaluable from
ObserverSnapshot. Per-room YAML checklists for 3 Gauntlet rooms plus
cross-room checks. Validation script + make checklist-validate/generate.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Makefile

@@ -5,7 +5,8 @@ GODOT := $(shell command -v godot4 2>/dev/null || command -v godot 2>/dev/null)
        db-backup db-install validate-content content-ron check-fact-ids setup-hooks \
        pre-pr pre-pr-lint pre-pr-build pre-pr-test pre-pr-validate pre-pr-fixtures \
        pre-pr-server pre-pr-client pre-pr-content \
-       fixtures-client
+       fixtures-client golden-diff golden-update \
+       checklist-validate checklist-generate
 
 # --- Configuration ---
 
@@ -39,6 +40,10 @@ help:
 	@echo "  make check-fact-ids    Check fact_id references against knowledge catalogs"
 	@echo "  make content-ron       Convert content YAML to RON (build-time)"
 	@echo "  make fixtures-client    Generate GDScript->Rust cross-encoder fixtures (#475)"
+	@echo "  make golden-diff        Show diff if golden file output has changed"
+	@echo "  make golden-update      Regenerate golden file and stage for commit"
+	@echo "  make checklist-validate Validate checklist YAML against schema"
+	@echo "  make checklist-generate Validate checklists + print condition summary"
 	@echo ""
 	@echo "  make pre-pr             Run all pre-PR checks (lint, build, test, validate, fixtures)"
 	@echo "  make pre-pr-server      Server-scoped pre-PR (lint, build, test, fixtures)"
@@ -121,6 +126,31 @@ fixtures-client:
 	cd server && cargo test --test serialization gdscript_generated_fixtures
 	@echo "--- Fixtures-client: PASS ---"
 
+golden-diff:
+	@echo "Regenerating golden output for comparison..."
+	@mkdir -p .cache/golden
+	@cp server/tests/golden/proof_room_tick_10.json .cache/golden/before.json
+	@cd server && UPDATE_GOLDEN=1 cargo test --test golden_suite -- proof_room_tick_10_matches_golden
+	@cp server/tests/golden/proof_room_tick_10.json .cache/golden/after.json
+	@cp .cache/golden/before.json server/tests/golden/proof_room_tick_10.json
+	@if diff -q .cache/golden/before.json .cache/golden/after.json >/dev/null 2>&1; then \
+		echo "--- Golden file: UP TO DATE ---"; \
+	else \
+		echo "--- Golden file has CHANGED ---"; \
+		echo ""; \
+		diff --color -u .cache/golden/before.json .cache/golden/after.json || true; \
+		echo ""; \
+		echo "Run 'make golden-update' to accept changes."; \
+		exit 1; \
+	fi
+
+golden-update:
+	@echo "Regenerating golden file..."
+	@cd server && UPDATE_GOLDEN=1 cargo test --test golden_suite -- proof_room_tick_10_matches_golden
+	@git add server/tests/golden/
+	@echo "--- Golden file updated and staged ---"
+	@echo "Review with: git diff --cached -- server/tests/golden/"
+
 test-client:
 	@test -n "$(GODOT)" || { echo "Godot not found. Run 'make setup' first."; exit 1; }
 	$(GODOT) --headless --path client -s res://addons/gdUnit4/bin/GdUnitCmdTool.gd --ignoreHeadlessMode -a res://tests/
@@ -240,6 +270,12 @@ validate-content:
 check-fact-ids:
 	@tooling/check-fact-ids
 
+checklist-validate:
+	@tooling/validate-checklist --check
+
+checklist-generate:
+	@tooling/validate-checklist
+
 content-ron:
 	cd tooling/content-converter && cargo build --release
 	tooling/content-converter/target/release/content-converter --input content --output content-ron --verbose