Deterministic symbol table on both x86 and arm64

[XiangpengHao]

Same training text will generate different symbol tables on x86 vs arm64.

The root cause is:

For speed, Rust's hash map checks slots in chunks using CPU vector instructions — and the chunk size is 16 slots at a time on Intel/AMD (SSE2) but 8 slots at a time on ARM (NEON).

Adding a third comparable makes sure that the symbols will never tie, i.e., a deterministic order regardless of the hash table implementation.

[codspeed-hq]

Merging this PR will improve performance by 14.31%

⚡ 2 improved benchmarks
✅ 28 untouched benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	Simulation	decompress-into-reuse	1.3 µs	1.1 µs	+14.64%
⚡	Simulation	decompress-into-reuse	1.8 µs	1.6 µs	+13.99%

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing deterministic-symbol-table (a3eef94) with develop (3661dcf)}