docs(milestone): complete v0.1 foundation

---ci---
phase: 0
milestone: v0.1
status: complete
---/ci---

scenarios/cost_rates.yaml

@@ -0,0 +1,20 @@
+# Praxis v0.1 cost rates — per-unit pricing for the cost logging (D-012, REQ-NFR-COST-01).
+# v0.1 logs actual per-session cost; no enforced ceiling (pilot).
+# Per G-005: these are pilot-config rates (Ollama tier + cloud), NOT at-scale
+# per-learner unit economics — the $3/learner target requires self-hosted
+# gemma4:e4b + Piper (post-pilot).
+
+# LLM role-play (gemma4:cloud) — Ollama tier (Pro plan amortized, pilot estimate).
+gemma4_cloud_per_1k_tokens_cents: 0.5
+
+# Debrief + classifier (deepseek-v4-flash:cloud) — Ollama tier.
+deepseek_v4_flash_per_1k_tokens_cents: 1.0
+
+# ASR (Deepgram Nova-3 streaming) — $0.0043/min → 0.43 cents/min.
+deepgram_per_audio_minute_cents: 0.43
+
+# TTS (Cartesia Sonic cloud) — per-char pricing (pilot estimate).
+cartesia_per_1k_chars_cents: 3.0
+
+# TTS (Piper self-hosted) — open-weights, $0 marginal cost.
+piper_per_1k_chars_cents: 0.0