pi_config

feat(pi): switch default to lemonade/Qwen3.6-35B-A3B-MTP-GGUF; add MTP model; use $LEMONADE_API_KEY

feat(pi): add lemonade provider with Qwen3.6-35B and Coder-Next builder models

fix(pi): remove rpiv-todo extension

chore(pi): lower qwen3-coder-next-builder contextWindow 114688 → 80000

fix(pi): gate rtk-rewrite off by default; raise reserveTokens to pi default