feat: spread shared automatic ports

[tt-a1i]

What changed

• deterministically spread shared automatic source/target ports in architecture, workflow, data-flow, and lifecycle renderers
• preserve single relationships and explicit via/channel/label geometry; sequence remains unchanged
• keep same-band lifecycle fan-out orthogonal
• document the default behavior and refresh the zero-install ZIP

Why

This is a bounded response to #6: high fan-out diagrams should not pile several arrows onto one node-side midpoint. It improves endpoint traceability without adding a graph layout engine, schema field, viewer control, or dependency.

Validation

• npm test: 404/404
• npm run test:webm: 2 Share Cards, copied Share Card, 9/9 unique WebM frames
• packaged ZIP: doctor, all five typed validations, showcase delivery, and high-fan-out packaged render
• ZIP freshness diff
• built-in browser: Signal Flow dark, Blueprint light, Classic dark; identical 8-edge geometry across all presets; Copy Share Card success

[cursor]

Bugbot is not enabled for your account, so this pull request was not reviewed.

Enable Bugbot in the Cursor dashboard to get automatic reviews on future PRs.