fix(viewer): clear selection on cluster collapse to kill ghost edges

[laurentftech]

Problem

In openlore view (clusters graph), collapsing a cluster while one of its member nodes was selected left the node-level selection edges rendering from the collapsed cluster's center — bright lines fanning out from an empty bubble to nodes across the graph. Since the "clear" button collapses all clusters, this also surfaced as ghost edges lingering after clear.

Root cause

The "Node-level edges when a node is selected" block in ClusterGraph.jsx renders whenever selectedId is set. Its position helper falls back to the cluster center:

if (nodeLayouts[clId]?.[nid]) return nodeLayouts[clId][nid];
return clusterPos[clId] || null;   // ← draws edge from collapsed cluster center = ghost

An existing guard in InteractiveGraphViewer.jsx clears the selection on the chat-driven collapse path, but toggleCluster (manual bubble click) never did — same bug class, uncovered path.

Fix

• toggleCluster: when collapsing the cluster that holds the selected node, clear selectedId/affectedIds (mirrors the chat-collapse guard).
• ClusterGraph selection-edge map: replace index key (key={i}) with a stable edge-id key so reconciliation can't leave stale <line>s.

Verification (browser automation)

• Collapse-while-selected: selection edges 9 → 0 after fix.
• Select / deselect / clear sequence: 0% pixel diff against a pristine baseline; DOM clean (0 selection lines, 0 node-glow).

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