Obsidian Vault sync / audit

Audit and maintain an existing Obsidian Vault against the current state of the repository it covers. Runs two parallel read-only scans (codebase + vault), produces a structured audit report across 11 checks (missing coverage, stale notes, dead wikilinks, orphan notes, tag drift, frontmatter drift, ADR staleness, canvas freshness, _AI-CONTEXT.md drift, Dataview query health, plugin recommendations), then applies fixes only after per-item user approval. Global and project-agnostic; pairs with the obsidian-vault creation skill. Trigger when the user says "maintain obsidian vault", "sync obsidian vault", "update obsidian vault", "audit obsidian vault", "obsidian-vault-sync", …