New endpoint — prompt scoring

POST /atoms/v1/prompt-scoring/score scores a single-prompt agent’s system prompt across 11 quality dimensions using Gemini-based analysis and returns an overall score (0–100), grade, token-density band, estimated first-token latency overhead, and per-dimension breakdowns.

Field	Description
`overall_score`	0–100 quality score
`overall_grade`	`Excellent` / `Good` / `Needs Work` / `Poor`
`band`	Token density: `lean` (under 4K tokens) / `normal` (4K–9.9K) / `heavy` (10K–14.9K) / `overweight` (15K+)
`estimated_ttft_overhead_ms`	Estimated first-token latency overhead from prompt length
`dimensions[]`	11 scored dimensions with `tier`, `level`, `title`, `description`, and `evidence_span`

Pass exactly one of versionId (published version) or draftId (agent draft) in the request body. The endpoint requires a minimum Member role and deducts 1 credit per call. Re-submitting an unchanged prompt returns a 400 — retrieve the cached result via GET /agent/{id} instead. Only single_prompt agents are supported; workflow-graph agents return 400.

→ Prompt Scoring reference