Cockpit Command Center: modernize graph navigation and dynamic detail panels

[smota]

Background & Problem Statement

Epic: #147

The current relationship graph is a useful list, but not a modern navigation surface. Users need to navigate goal -> evidence -> decision -> PR -> follow-up with dynamic details.

Proposed Solution

Implement modern graph navigation MVP with selectable nodes, badges/icons, filters, and a dynamic detail panel.

Requirements

• Graph nodes: goal, goal group, role contribution, decision, validation, review, PR, commit, follow-up, human gate.
• Edges: implements, closes, blocks, depends-on, spawned-follow-up, validated-by, reviewed-by, returned-to-dev.
• Node icons/badges by type and state.
• Selecting a node updates detail panel with summary, evidence, next action, durable link.
• Progressive HTML/SVG MVP acceptable; avoid decorative-only graph.

Acceptance criteria

• Graph navigation supports selecting nodes.
• Detail panel changes by selected node.
• Badges/icons distinguish node types.
• Graph links to durable GitHub evidence.
• Works gracefully when graph sparse.

Test plan

• Graph view-model tests.
• UI snapshot tests for node/detail rendering.
• Manual navigation review.

Workflow classification

Product UI issue.

[github-actions]

Integrated into development by PR #155: #155

Merge commit: aefe4d9f7d159ccf04d29a4490c4b1c40269e81c
Release/promotion to main is tracked separately.