🚀 Transformers.js v4.1 — Gemma 4, KV cache improvements, and new quantization dtypes

• Add support for Gemma 4 in #1627
• Cached generation improvements (+ past_key_values via pipeline function) in #1638
• Improve tokenizer types based on input function parameters in #1641
• Add support for q1, q1f16, q2, and q2f16 data types in #1647
• Re-enable SmolVLM in #1648
• Update default generation parameters in #1649
• Pin GitHub Actions to commit SHAs in #1626

Full Changelog: 4.0.0...4.1.0