Get Kg Node Source

Return the jeevy source DB row that backs a KG node — the "DB record" peek.

Resolves canonical_id (a KG node UUID) -> canonical_key -> source table + PK -> SELECT * from that table, for projection QA (compare source DB against projected facts). PK-keyed node types (job/task/workstream/line_item/user/ personnel): found=True + a redacted row. Name-keyed or composite-keyed types (part, bom-line, organization, vendor, ...): found=False + a reason, not a 500.

Denylisted columns (security_gates.redact_row -> capture_denylist) are stripped before the row is returned — mirrors internal.py's get_kg_node_source_internal, behind user-auth.