feat(ghost-drift): add describe verb for selective fingerprint reads

[nahiyankhan]

Summary

• New CLI verb ghost-drift describe prints a section map of fingerprint.md (frontmatter range, body sections, per-dimension decision blocks) with line ranges and token estimates, so host agents can selectively load only the sections they need instead of loading the whole file.
• Skill recipes (review.md, generate.md) now open with describe and teach a recall safety rule: when uncertain which decisions are relevant, load the entire # Decisions block — typically 2–4k tokens, cheaper than missing a constraint.
• New library exports: layoutFingerprint, formatLayout, FingerprintLayout, FingerprintLayoutSection.

Why

Typical fingerprints run 3–5k tokens, and the # Decisions block alone is usually 60–80% of that. Most agent reads (a PR review, a single-component generation) don't need every dimension. describe is the deterministic answer to "what's in this file and where" — line ranges are 1-indexed and inclusive, dropping straight into a Read tool's offset / limit = end - start + 1.

A deliberate non-decision: no [partition] hints next to decision sections. A heuristic dimension→partition mapping that looks authoritative would cause agents to skip relevant decisions; the recall safety rule in the recipe is the right place for that judgement, not the deterministic primitive.

Sample output

Run against packages/ghost-ui/fingerprint.md:

fingerprint.md — 309 lines, ~3,955 tokens

FRONTMATTER    1–164      ~973 tok        [palette, spacing, typography, surfaces, roles, observation, decisions]
# Character      166–169    ~159 tok
# Signature      170–179    ~298 tok
# Decisions      180–305    ~2,503 tok
  ### color-strategy           182–192    ~250 tok
  ### shape-language           205–216    ~181 tok
  ### typography-voice         217–229    ~258 tok
  …
# Fragments      306–309    ~21 tok

Test plan

• pnpm exec vitest run packages/ghost-drift — 182 tests pass (7 new in test/fingerprint/layout.test.ts)
• pnpm check — biome + typecheck + file-size + docs-frontmatter + cli-manifest all clean
• just build-ui — docs site builds; new Inspection — describe section renders with <CliHelp command="describe" /> from auto-generated manifest
• Manual run on packages/ghost-ui/fingerprint.md (cli + json formats)
• Reviewer: confirm the recall safety rule wording in review.md / generate.md is appropriate for the recipe's tone