Banker's Wrapped v1.8.1

The first live post-flip run exposed that WS-1's chat path could never reach NVIDIA NIM: the
Genblaze chat wrapper always posts to GMI's endpoint, so nvidia-nim/...-prefixed ids (and the
documented "NIM fallback") 404'd — only mocked tests exercised the route. Found before any
credits were burned (the 404 bills nothing).

Fixed

• Real NVIDIA NIM routing (GenblazeClient.generate_script_text): nvidia-nim/-prefixed
  model ids are stripped and redirected to NIM's OpenAI-compatible endpoint via the SDK chat
  wrapper's base_url override (new nvidia_nim_api_key / nvidia_nim_base_url client params).
  Provider provenance is derived from the route actually taken, not the model-id prefix.
• Automatic NIM fallback now exists (NarrativeAgent._try_genblaze): after the primary
  model exhausts its attempts (provider failure or invalid JSON), one final SDK-routed attempt
  runs against NVIDIA NIM — previously claimed in docs but not implemented.
• GMI_CHAT_MODEL default was invalid: GMI's catalog serves no meta-llama/* models
  (verified via GET /v1/models). Production model is now openai/gpt-5.4-mini
  ($0.75/$4.50 per M tokens ≈ $0.005/run); both routes live-validated with 1-token probes.
• llm.cost_usd in generation.json is now computed from GMI's published per-token pricing
  when the SDK reports none (the SDK intentionally returns cost_usd=None); NIM runs record $0.

Changed

• 5 new tests (NIM-fallback success/exhaustion in NarrativeAgent; chat routing +
  cost computation in GenblazeClient); coverage 97.8%.
• Docs sweep: README (pipeline diagram, timing table, tech stack, models_used example,
  release badge → releases/latest), DEVPOST providers table, COSTS per-run table,
  CLAUDE.md, .env.example — all reflect GMI openai/gpt-5.4-mini primary + NIM fallback.

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