feat: comprehensive refactoring and feature enhancements

[shengyanli1982]

Major Changes:

• Refactor MemoryCache architecture: remove bucketWrapper abstraction and inline bucket access logic for improved performance
• Replace global callback with per-element callback support, enabling fine-grained event handling
• Add bucketMask field for faster bucket indexing via bitmask operation

New Features:

• Add ReasonCleared callback reason for Clear() operation to notify alive non-expired elements
• Add GetTTL() method to retrieve key expiration time without modifying it
• Add GetWithTTL() method to get value and refresh expiration time atomically
• Add UpdateTTL() method to update key expiration without retrieving value
• Add Len() method for quick element count (includes uncleaned expired elements)
• Add adaptive TTL check interval: dynamically adjusts cleanup frequency based on deletion volume

Performance Optimizations:

• Optimize heap operations with inline lessByIndex() and swapDirect() methods
• Convert recursive heap Up/Down to iterative implementation, reducing call stack overhead
• Add safety checks to heap Front() to prevent out-of-bounds access
• Use time.Now() caching via atomic timestamp (CachedTime option) to reduce syscall overhead
• Pre-compute bucketMask during initialization for O(1) bucket lookup

Bug Fixes & Reliability:

• Fix Stop() goroutine synchronization: move wg.Add(2) before goroutine spawn to prevent race conditions
• Validate MinInterval/MaxInterval ordering in options initialization
• Fix Fnv hash functions to iterate bytes instead of runes for correct string hashing
• Add mc.Stop() defer in benchmark tests to prevent resource leaks

Documentation:

• Update README with comprehensive API documentation, options table, and improved examples
• Add Clear() and Range() callback deadlock warnings in Chinese/English
• Improve method descriptions with explicit behavior specifications

Code Quality:

• Remove deprecated bucketWrapper abstraction layer
• Remove _ from range statements (Go idiomatic cleanup)
• Remove unnecessary algo.Min dependency in heap
• Clean up .editorconfig and .golangci.yaml configuration files
• Update Map interface parameter naming for clarity

Config Changes:

• Add CachedTime option (default: true) for timestamp caching
• Add MinInterval/MaxInterval for adaptive cleanup tuning
• Remove global callback field from MemoryCache struct

[lxzan]

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