Creates a typed, directed edge between two pages — the knowledge graph's connective tissue. Canonical directions: PERSON or ROLE owns WORKFLOW/SYSTEM/PRIORITY, PERSON or ROLE involved_in WORKFLOW, PERSON holds ROLE, WORKFLOW uses SYSTEM, SYSTEM uses SYSTEM, PAIN_POINT affects WORKFLOW/SYSTEM/PERSON/ROLE, DOCUMENT documents anything, PRIORITY contributes_to PRIORITY (a priority that ladders up to a bigger one; each ladders up to at most one, and choosing a new one moves it; a priority has one owner the same way), UNIT part_of UNIT and ROLE or PERSON part_of UNIT (the org chart: one parent each; a UNIT's lead owns it, one owner), relates_to as fallback. Prefer attaching responsibilities to the ROLE and linking the PERSON to it with holds — the role outlasts whoever is in it. Pass validFrom / validTo when the source says when it was true ('took over approvals in March'), and sourceKind + sourceId for who said so (the interview or page you learned it from). Idempotent on an open (from, to, kind) edge — re-creating one returns it. May return `needs_confirmation`; tell the user what you're proposing, wait for their approval, then re-call with the approvalId.