feat(turbo): add PQ int4/int8 quantizers and PQFast FastScan support

[zzlin237]

• Add PqInt4Quantizer / PqInt8Quantizer with ADC/SDC/batch distance kernels for avx2, avx512, neon and scalar, plus precomputed residual distance table support for IVF search
• Add PqFastQuantizer (QuantizeType::kPQFast): 4-bit PQ with FastScan packed-block scan kernels (32 vectors per block, affine-quantized LUT)
• Wire PQ build/search params through index_param and index_param_builders
• Add unit tests for int4/int8/fast quantizers and FastScan kernels
  The specific performance metrics are as follows:

sift

• centroid_count：1024
• num_chunk：32，64
• use_residual: true
• nprobe: 8, 16, 32
• metric：l2

num_chunk	nprobe	fast recall	int4 recall	fast 精排后	int4 精排后	fast QPS	int4 QPS	加速比
32	8	56.88%	56.92%	81.65%	80.88%	15868	15509	1.02×
32	16	58.89%	59.39%	88.41%	88.19%	14984	14443	1.04×
32	32	59.88%	60.21%	91.83%	91.58%	13510	11834	1.14×
64	8	68.46%	68.86%	82.93%	82.63%	15342	15092	1.02×
64	16	72.45%	73.07%	91.92%	91.75%	14351	13154	1.09×
64	32	74.36%	75.00%	96.95%	96.97%	12607	9441	1.34×

gist

• centroid_count：1024
• num_chunk：240，480
• use_residual: true
• nprobe: 8, 16, 32
• metric：l2

num_chunk	nprobe	fast recall	int4 recall	fast 精排后	int4 精排后	fast QPS	int4 QPS	加速比
240	8	42.47%	42.41%	56.90%	56.77%	10939	7395	1.48×
240	16	47.61%	47.60%	70.28%	70.40%	8427	4741	1.78×
240	32	50.26%	50.36%	79.91%	80.07%	5758	2805	2.05×
480	8	52.22%	53.45%	57.26%	58.04%	8591	4308	2.00×
480	16	63.08%	64.37%	73.14%	73.37%	5900	2497	2.36×
480	32	69.74%	71.37%	85.78%	86.24%	3707	1371	2.70×

cohere

• centroid_count：1024
• num_chunk：192，384
• use_residual: true
• nprobe: 8, 16, 32
• metric：cosine

num_chunk	nprobe	fast recall	int4 recall	fast 精排后	int4 精排后	fast QPS	int4 QPS	加速比
192	8	53.76%	53.89%	74.58%	74.63%	9709	4616	2.10×
192	16	56.89%	57.03%	81.66%	81.85%	7014	2826	2.48×
192	32	58.39%	58.60%	85.67%	85.86%	4610	1708	2.70×
384	8	72.22%	72.18%	79.11%	79.06%	7548	2573	2.93×
384	16	77.76%	77.77%	88.20%	88.17%	5047	1508	3.35×
384	32	80.70%	80.81%	93.95%	94.01%	3188	877	3.64×

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