fix: cache routing, clear failures button, separate music/SFX controls

[TheBestFisch]

Summary

• Fix Introducing a Cache to only one service prevents routing to other #88: Cache routing bug — compute now verifies the cache can reach the request's final destination before routing through it. Also adds s3 fallback for cdn-destined requests at both the compute and cache forwarding stages.
• Fix Clear-able failures list #115: Adds a "Clear" button to the failures panel, allowing players to reset failure counters mid-game without restarting.
• Fix Separate sound effects and music control #112: Splits the single mute toggle into separate Music and SFX buttons (in both the in-game toolbar and the main menu). All inline new Audio() calls replaced with SoundService methods so they respect the SFX mute state.
• Adds i18n keys (clear, music, sfx) to all 5 locale files (EN, ZH, PT-BR, DE, NEP).

Test plan

• Start a Survival game, place Compute → Cache → DB (no S3 connected to cache). Verify STATIC/UPLOAD requests are routed directly to S3 instead of through cache.
• Place Compute → Cache → DB → S3. Verify READ/SEARCH requests go through cache to DB, and STATIC requests go through cache to S3.
• Play until failures appear, click the "Clear" button — verify counters reset to 0 and panel hides.
• Toggle Music off — verify background music stops but SFX (place, connect, success sounds) still play.
• Toggle SFX off — verify procedural tones and click sounds stop but music continues.
• Toggle both off and on — verify correct icon states on both toolbar and menu buttons.
• Switch language and verify "Clear", "Music", "SFX" labels translate correctly.

🤖 Generated with Claude Code

[pshenok]

@TheBestFisch resolve conflict please. "Clear" button - already done before.