Board-verify int8 FunctionGemma (numeric quality, speed, RAM)

[michalharakal]

int8 weight-only quant (GEMMA_QUANT=int8) is export-verified on CPU (transformers PR #245). On-device, confirm:

• Numeric quality of per-row symmetric int8 from Q5_K (oracle token-for-token check).
• Decode speed vs bf16.
• RAM claim: irpa 831 → ~415 MiB on the 1.9 GB board.
• iree-compile (Torq-fork) accepts the in-graph dequant (i8→f32 × scale).

Tracker: sl2610-function-calling/docs/GEMMA-KV-INT8.md.