feat(mcp): knowledge-graph resource

[radimsem]

Type: AFK

What to build

Read-only MCP resource exposing the relations graph for visualization: resolved edges plus pending/unresolved edges plus the node set needed to render them. The weight wiki-link syntax ([[X; w=4.2]], <knowledge weight="2.43">) already parses into relations / pending_relations — this slice is purely exposure, the core "brain" graph view.

remindb://graph →
{ "nodes":   [ { "id": "", "label": "", "type": "", "temperature": 0.0 } ],
  "edges":   [ { "source": "", "target": "", "weight": 1.0, "origin": "parsed|manual" } ],
  "pending": [ { "source": "", "target_label": "", "target_source": "",
                 "target_id_hint": "", "weight": 1.0, "origin": "" } ] }

Acceptance criteria

• Resource lists + reads; resolved edges from relations, pending from pending_relations
• Weight and origin included; pending edges distinguishable from resolved
• Reuses existing store relation queries — no new traversal logic
• Follows the feat(mcp): resource infrastructure + overview resource #104 resource contract (passive: no boost, no OpMu, no snapshot)
• skills/remind/SKILL.md updated
• Test on a fixture with parsed + manual + pending edges
• make test green

Blocked by

• feat(mcp): resource infrastructure + overview resource #104