huge performance gains with transformers fix

[tpae]

Summary

I found latency issues with generateEvents function, and found out that swift-transformers package needed some optimization.

PR -> huggingface/swift-transformers#218
PR -> ml-explore/mlx-swift-examples#380

The results before:

Running warm-up: 3 server(s), 2 prompt(s), 1 iteration(s) each, concurrency=1 (excluded from results)...
Running benchmark against 3 server(s), 2 prompt(s), 10 iteration(s) each, concurrency=1, system_prompt=ON...

Summary:
- osaurus | llama-3.2-3b-instruct-4bit:
  success_rate=100.0%  ttft_avg=222.5ms  ttft_p50=214.7ms  ttft_p95=248.3ms  total_avg=1272.1ms  p50=1190.7ms  p95=2062.5ms  chars/s=480.1  bytes/s=480.1
- ollama | llama3.2:
  success_rate=100.0%  ttft_avg=58.3ms  ttft_p50=52.0ms  ttft_p95=90.5ms  total_avg=1632.0ms  p50=1485.5ms  p95=3009.4ms  chars/s=438.9  bytes/s=438.9
- lmstudio | llama-3.2-3b-instruct:
  success_rate=100.0%  ttft_avg=55.5ms  ttft_p50=50.5ms  ttft_p95=94.9ms  total_avg=1171.7ms  p50=1131.3ms  p95=2092.3ms  chars/s=623.0  bytes/s=623.0

The results after 🤯:

Running warm-up: 3 server(s), 2 prompt(s), 1 iteration(s) each, concurrency=1 (excluded from results)...
Running benchmark against 3 server(s), 2 prompt(s), 10 iteration(s) each, concurrency=1, system_prompt=ON...

Summary:
- osaurus | llama-3.2-3b-instruct-4bit:
  success_rate=100.0%  ttft_avg=84.2ms  ttft_p50=82.4ms  ttft_p95=87.4ms  total_avg=1330.3ms  p50=1192.0ms  p95=2433.8ms  chars/s=560.6  bytes/s=560.6
- ollama | llama3.2:
  success_rate=100.0%  ttft_avg=59.7ms  ttft_p50=52.0ms  ttft_p95=93.6ms  total_avg=1690.4ms  p50=1453.2ms  p95=3222.2ms  chars/s=439.4  bytes/s=439.4
- lmstudio | llama-3.2-3b-instruct:
  success_rate=100.0%  ttft_avg=55.5ms  ttft_p50=50.7ms  ttft_p95=92.8ms  total_avg=1143.6ms  p50=1092.0ms  p95=2087.0ms  chars/s=613.2  bytes/s=613.2

Checklist

• I have read CONTRIBUTING.md
• I added/updated tests where reasonable
• I updated docs/README as needed
• I verified build on macOS with Xcode 16.4+

[tpae]

Related to #47