feat(providers/{image,video}): real Higgsfield adapter via MCP (Soul / DoP / Seedance)

[wesleysimplicio]

Context

HiggsfieldProvider (image) at lib/providers/image.ts:44-46 and HiggsfieldVideoProvider at lib/providers/video.ts:36-38 are mocks. Per AGENTS.md, HIGGSFIELD_MCP_ACTIVE=true indicates the Higgsfield MCP is globally active. Per ROUTING-MATRIX.md, Higgsfield is the default for cinematic images and reels, motion control, editorial portraits.

Goal

Real adapter that delegates to the Higgsfield MCP server (Soul 2.0, DoP, Seedance 2.0).

Acceptance criteria

• Adapter reads HIGGSFIELD_MCP_ACTIVE from env; if false, throw clearly
• Image side: calls Higgsfield Soul/DoP MCP tool with assembled prompt + params (delegates prompt assembly to higgsfield-prompt-builder skill)
• Video side: calls Seedance MCP tool with prompt + duration + aspect
• Polls for completion if the MCP returns a job ID (timeout 5min, configurable)
• Downloads asset bytes to outputs/<client>/<date>/<piece-id>/
• Real cost_usd from Higgsfield pricing table
• Retry + timeout via shared policy
• Skipped when DRY_RUN=true
• E2E spec with mocked MCP transport

Files

• lib/providers/image.ts:44-46
• lib/providers/video.ts:36-38
• .skills/higgsfield-prompt-builder/SKILL.md (reference only)

[wesleysimplicio]

Closed after PR #40 follow-up stabilization in commit f40b58d. Current main passes npm run typecheck and npm run test:e2e (119 Playwright specs green), and this tracker item is being retired per repository cleanup.