A new SurrealDB verification skill, a lede-length discipline propagated across two skills, and sync-skills-symlinks preps for an agent-skills migration

A skill for querying a SurrealDB canonical layer directly instead of writing a throwaway Node script per check. Plus: the lede field was drifting toward mini-essays, so changelog-conventions and context-vigilance both got a 'subtitle-length, not a paragraph' rule with the same wording. Plus: sync-skills-symlinks.sh now recognizes a context-v/agent-skills/ layout alongside the legacy context-v/skills/ one, ready for a migration that hasn't moved any actual skill directories yet.