Refactor Gache for Performance and Stability

[kpango]

• Implemented Arena-based storage in map.go to eliminate pointer scanning and reduce GC overhead.
• Introduced O(1) Timing Wheel expiration mechanism integrated into shards.
• Added global atomic time caching to reduce syscall frequency.
• Implemented incremental expired processing to avoid CPU spikes.
• Utilized sync.Pool for notification structs to minimize allocation.
• Updated gache.go to support new Map implementation and non-blocking expiration notifications.
• Added comprehensive functional tests covering basic operations, expiration, range, clear, and concurrency.
• Removed obsolete map implementation tests.

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PR created automatically by Jules for task 1877846128182509760 started by @kpango

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