Add explicit guidance selection to review

[nahiyankhan]

Stack: Depends on #292. Base is fix/preserve-guidance-output so this diff contains only explicit-guidance review. Land #292 first, then retarget/rebase this PR onto main.

Category: new-feature
User Impact: Review can consider the brand guidance used to build a new surface even when its referenced components or materials did not change.

Problem: Diff-based material matching can miss an unchanged button's guidance when a new checkout uses that button. The host knows which guidance governed the work, but could not supply it to review.

Solution: Add repeatable ghost review --node <id> to include exact, host-selected guidance and offer referencing checks alongside existing material matches and always-offered checks. Preserve full guidance, material declarations, and selection provenance; unknown IDs fail before reading the diff, and no-flag behavior stays unchanged.

ghost review --node component.button --node principle.trust

No receipts, import scanning, truncation, new dependencies, or starter changes. Explicit selection adds review context; it does not prove applicability, create file matches, or suppress coverage gaps.

Validation:

• pnpm run quality:all: passed, repeated by the pre-push hook. 264 tests across 21 files, including 32 new tests, plus builds, typecheck, packed-consumer installation/imports, release checks, workspace checks, and package validation.
• Built CLI smoke: unchanged-component check is offered with explicit selection; guidance and unmatched-file gaps remain present.
• ghost manifest --format json: exposes repeatable --node <id>; help/manifest behavior covered by tests.
• pnpm check:terminology and merge-base diff checks: passed.
• Existing lint warnings and two cover-policy warnings remain unchanged.

Changeset: minor added for the new flag and additive packet fields. Existing review JSON/Markdown behavior is unchanged without explicit IDs.

ghost Review:

• node packages/ghost/dist/bin.js review --package apps/docs/.ghost --base origin/fix/preserve-guidance-output --format json: packet assembled; no docs-material matches or offered checks. All 12 changed files are outside that package's material coverage, so this is a coverage gap, not a passing grade.
• Independent source review found no blockers. Current CLI manifest used; retired check/manifest-generation workflows are not available in this checkout.

File changes (12 files)

File	Purpose
.changeset/explicit-review-guidance.md	Release note for additive explicit-node review.
packages/ghost/README.md	Explain reviewing guidance behind unchanged components.
packages/ghost/src/commands/command-discovery.ts	Advertise explicit guidance in review discovery.
packages/ghost/src/commands/review-command.ts	Parse repeatable IDs and validate before diff access.
packages/ghost/src/review/resolve.ts	Validate exact identities, widen check selection, and preserve provenance and gaps.
packages/ghost/src/review/review-packet.ts	Include complete explicit guidance/material declarations and deduplicate overlaps.
packages/ghost/src/skill-bundle/SKILL.md	Teach additive review selection.
packages/ghost/src/skill-bundle/references/making.md	Ask the host to supply guidance that governed this change, not every prior pull.
packages/ghost/src/skill-bundle/references/schema.md	Document selection, error, and packet-field behavior.
packages/ghost/test/review-explicit-packet.test.ts	Cover full content, baseline preservation, overlap, cover/nested IDs, and long guidance.
packages/ghost/test/review-node-cli.test.ts	Cover repeated flags, validation order, missing values, check-directory behavior, and help.
packages/ghost/test/review-selection.test.ts	Cover exact IDs, mixed/anchored references, stable selection, and non-filtering behavior.

Screenshots/Demos: N/A; no visual changes.