⚡ Bolt: Optimize cache key generation and fix ESLint errors

[suranig]

💡 What:

• Precomputed the static portion (prefix + version) of cache keys in createCacheHandler.ts.
• Replaced dynamic array generation, .filter(Boolean), and .join(':') with simple template literal string concatenation inside the getFullKey hot path.
• Fixed ESLint errors in src/backends/index.ts by using closures to avoid non-null assertions and adding // eslint-disable-next-line no-console where logging was intentional.
• Added a destroy method to CacheHandler to properly clear the l1Cache cleanup interval and prevent memory leaks.

🎯 Why:
Dynamically allocating arrays and using higher-order functions like .filter and .join on every single cache fetch creates unnecessary memory pressure and CPU overhead in Node.js/V8. For a high-throughput cache handler, string concatenation with precomputed static prefixes is significantly more efficient. The ESLint fixes ensure code quality standards are met, and the destroy method fixes a potential memory leak with dangling intervals.

📊 Impact:
Eliminates array allocation and iteration overhead per cache hit/miss. While a micro-optimization per call, over millions of cache fetch operations in a high-traffic Next.js application, this reduces garbage collection pauses and CPU load, noticeably improving throughput.

🔬 Measurement:
Verify the functionality by running the test suite (npm run test), which asserts that cache keys are correctly generated. Check memory and CPU profiles under high load (e.g., using autocannon) before and after the change; you should observe a reduction in minor garbage collection events related to short-lived arrays.

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PR created automatically by Jules for task 8476630633563781973 started by @suranig

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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