feat: adopt OKF v0.2 output

[JHSeo (JHSeo-git)]

Closes #580

Updates OpenWiki's OKF output from v0.1 to OKF v0.2. This is the Phase 1 (core producer/validator) scope from the issue; emitting the sources provenance field from openwiki.source_paths is left as a follow-up.

Changes

Producer

• The bundle-root index.md now declares okf_version: "0.2" (src/okf/index-sync.ts). The deterministic index sync rewrites existing root indexes on the next run, so existing wikis migrate automatically.
• All five system-prompt OKF blocks (code chat/init/update, personal chat/init/update) now target the v0.2 schema and instruct generated: {by, at} in place of the superseded timestamp (SPEC §13.1). The producer actor is injected deterministically as openwiki/<version> via a new {OKF_PRODUCER_ACTOR} placeholder resolved in createSystemPrompt from OPENWIKI_VERSION, following the §7 actor convention.
• Prompts tell the agent to drop a page's legacy timestamp only when it meaningfully changes that page, so untouched pages are not churned.

Validator (src/okf/frontmatter.ts)

• New shape checks for the optional v0.2 families when present, per §5: generated (mapping with a required non-empty by), verified (a {by, at} mapping or list of them — a bare mapping is read as a one-element list per §5.2), sources (list of mappings each with a non-empty resource), status (draft | stable | deprecated), and stale_after (YYYY-MM-DD).
• Stays permissive per §11: absent families and unknown extension keys are never flagged, and the legacy timestamp is still accepted as a non-empty string (v0.1 fallback).
• Like the existing checks, these only feed the post-write warning that nudges the agent to fix a page; nothing is rejected or rewritten.

Docs

• README OKF section updated to v0.2; changeset added (minor).

Notes for review

• status is now enum-validated because v0.2 §5.4 defines a closed set. A page using status as a free-form producer extension (valid under v0.1) gets a correction warning the next time the agent writes it. If you prefer to keep status unvalidated for backward compatibility, I'm happy to relax that check.
• The repository's own openwiki/index.md still says 0.1; it is generated, so I left it for the scheduled refresh workflow rather than hand-editing.

Testing

• Test-first: updated/added cases in test/index-middleware.test.ts, test/prompt-okf.test.ts, and test/frontmatter-validator.test.ts (v0.2 families accepted, malformed families reported, bare verified mapping accepted, legacy timestamp still accepted), watched them fail, then implemented.
• pnpm test (914 passed), pnpm typecheck, pnpm lint:check, and pnpm format:check are all clean.

[changeset-bot]

🦋 Changeset detected

Latest commit: 9f78f3e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
openwiki	Minor

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