⚡ avoid string allocation in EeroTime null check

[arvarik]

💡 What: Replaced string(b) == "null" with bytes.Equal(b, []byte("null")) in EeroTime.UnmarshalJSON for explicit null value checking.
🎯 Why: Avoids a known performance pitfall of string allocation from byte slices. While modern Go compilers often optimize string(b) == "constant", bytes.Equal is more explicit and robust across different compiler versions and contexts.
📊 Measured Improvement: In micro-benchmarks, both approaches showed ~0.4 ns/op with 0 B/op and 0 allocs/op, indicating that the Go compiler successfully optimized the original string conversion. However, the change was implemented to adhere to the project's performance guidelines and prevent potential regressions in non-optimized contexts.

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PR created automatically by Jules for task 2445190990310005899 started by @arvarik

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