[fallintoplace]

What

• Avoid a temporary heap string when encoding bytes fields up to 192 bytes.

Why

• Small ProtoJSON bytes fields currently allocate a String for base64 output.

Implementation

• Encode up to 192 input bytes into a 256-byte stack buffer.
• Keep the existing path for larger fields.

Benchmark

• New vs old, Criterion (80 samples, 2 runs): 8/32/96/192 B: 23/43/92/176 ns vs 50/70/121/201 ns.
• 193 B: 205-210 ns vs 205-208 ns. 4096 B: 3.39-3.40 us both; no measurable change.

[github-actions]

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