Store OKF metadata inside wiki nodes

[humandebri]

Purpose

Promote OKF alignment from Context Pack export compatibility to the internal Kinic Wiki node data model.

Changes

• Add OKF metadata helpers and fixed OKF type handling in wiki_domain.
• Backfill metadata_json with okf_type, resource, source_refs, and trust_level through wiki_store:006_okf_metadata.
• Recompute source_refs from /Sources/evidence/... body links and refresh metadata after write, append, edit, multi-edit, and move flows.
• Require database-aware FS migrations and remove the db_local migration default.
• Prefer metadata over path inference in Context Pack export, with body scan only when metadata is absent.
• Update docs and clients to use evidence source terminology.
• Integrate the PR with refactor/four-store-terminology, including /Wiki root, database profile, store manifest, and Candid interface changes from the base branch.

Validation

• cargo test -p kinic-wiki-domain okf_metadata_recomputes_existing_source_refs_from_content
• cargo test -p kinic-wiki-domain okf_metadata_clears_source_refs_when_content_has_none
• cargo test -p vfs-runtime okf_source_refs_follow_runtime_content_mutations
• cargo test -p vfs-store fs_migrations_backfill_okf_metadata_and_sync_updates
• cargo test -p kinic-vfs-cli export_prefers_okf_metadata_over_path_inference
• cargo test -p vfs-store --test fs_store_vfs
• /Users/0xhude/Desktop/MyCLI/checker/lint.sh
• /Users/0xhude/Desktop/MyCLI/checker/check.sh
• git diff --check

Impact

• Base branch: refactor/four-store-terminology.
• Candid public interface includes the base branch profile/store-manifest shape and the checked-in vfs.did is regenerated.
• Existing nodes receive metadata backfill and etag/update-log changes through the new store migration.