Fix oxlint --deny-warnings and eliminate all biome-ignores

--deny warnings was a no-op (not a valid category); the correct flag
is --deny-warnings. Fixed all 8 pre-existing warnings and removed
every biome-ignore from source and test files. Simplified the check
script to zero-tolerance: any biome-ignore now fails the build.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/domain/src/__tests__/conditions.test.ts

@@ -47,8 +47,8 @@ describe("getConditionDescription", () => {
 				(d.systems.includes("5e") && d.systems.includes("5.5e")),
 		);
 		for (const def of sharedDndConditions) {
-			expect(def.description, `${def.id} missing description`).toBeTruthy();
-			expect(def.description5e, `${def.id} missing description5e`).toBeTruthy();
+			expect(def.description).toBeTruthy();
+			expect(def.description5e).toBeTruthy();
 		}
 	});