fix: normalize ambience loudness for v0.2.5

.agent/evidence-v0.2.5/12-integrity-RED.log

@@ -0,0 +1,25 @@
+
+ RUN  v5.0.4 /home/hermes/worktrees/find-word-v0.2.5
+
+ ❯ tests/audio-integrity.test.ts (0 test)
+
+⎯⎯⎯⎯⎯⎯ Failed Suites 1 ⎯⎯⎯⎯⎯⎯⎯
+
+ FAIL  tests/audio-integrity.test.ts [ tests/audio-integrity.test.ts ]
+Error: Cannot find module '../src/audio/integrity' imported from /home/hermes/worktrees/find-word-v0.2.5/tests/audio-integrity.test.ts
+ ❯ tests/audio-integrity.test.ts:4:1
+      2| import { readFileSync } from "node:fs";
+      3| import { expect, it } from "vitest";
+      4| import { verifyAudioAsset } from "../src/audio/integrity";
+       | ^
+      5|
+      6| // 신뢰 기준은 JS 번들에 고정한 manifest다. 요청 파일이 자기 해시를 선언할 수 없다.
+
+⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯[1/1]⎯
+
+
+ Test Files  1 failed (1)
+      Tests  no tests
+   Start at  10:23:35
+   Duration  268ms (setup 89%, transform 7%, worker 4%)
+