Update Relay generation docs

[nahiyankhan]

Category: fix
User Impact: Users see the supported Relay gather workflow instead of a removed context-bundle command.
Problem: Several lower-level docs still described generation context through ghost emit context-bundle, but the current CLI intentionally rejects that emit kind. That leaves readers with a stale command path when they are trying to brief an agent before generation.
Solution: Point generation-context documentation at ghost relay gather, name the ghost.relay.gather/v1 adapter contract, and keep the fingerprint-first architecture memo aligned with the current lifecycle language.

Validation:

• pnpm exec vitest run packages/ghost/test/cli.test.ts packages/ghost/test/skill-bundle-manifest.test.ts packages/ghost/test/public-exports.test.ts: passed, 51 tests
• pnpm check:docs: passed
• pnpm check:install-bundle: passed
• pnpm check:cli-manifest: passed
• pnpm check:terminology: passed
• git diff --check: passed
• pre-commit pnpm check: passed
• pre-push pnpm build: passed
• pre-push pnpm check: passed
• pre-push pnpm test: passed, 36 files / 358 tests

Changeset: added patch changeset for public docs that affect @anarchitecture/ghost users.

Ghost Review:

• node packages/ghost/dist/bin.js check --base origin/main: passed, no active deterministic check failures
• node packages/ghost/dist/bin.js review --base origin/main --include-memory: advisory packet generated for the docs diff; no blocking checks selected

File changes

.changeset/bright-relay-docs.md
Adds a patch changeset for the public documentation correction.

docs/fingerprint-format.md
Replaces the removed ghost emit context-bundle example with ghost relay gather and renames context-bundle wording to Relay briefs.

docs/generation-loop.md
Adds the current pre-generation ghost relay gather command to the generation loop.

docs/host-adapters.md
Documents ghost relay gather [target] --format json as the generation-context adapter contract and includes it in custom memory-dir examples.

docs/ideas/fingerprint-first-architecture.md
Updates lifecycle and rationale language from context/generation packets to Relay briefs and relay gather.

Screenshots/Demos: N/A, documentation-only change.