feat: selective endpoint export with checkboxes (GLA-52)

[paoloanzn]

Summary

• Add checkbox per endpoint row to include/exclude from API map export
• "All" / "None" selection controls in the Endpoints pane header
• Export Map button disables when no endpoints are checked
• New endpoints auto-check when discovered during live capture
• Stale endpoint keys are cleaned up when entries change

Test plan

• Trigger network activity — verify all endpoint rows have checkboxes, all checked by default
• Uncheck some endpoints, click "Export Map" — verify exported JSON only contains checked endpoints
• Click "None" — verify all unchecked, Export Map button disables
• Click "All" — verify all re-checked, Export Map button enables
• Trigger new requests to a new endpoint — verify new row appears auto-checked
• Verify clicking a checkbox does NOT change the selected (highlighted) endpoint in the detail pane
• Verify clicking the row area (not checkbox) still selects the endpoint for detail view

🤖 Generated with Claude Code

[linear]

GLA-52 Selective endpoint export

In the map UI, allow the user to select which endpoints to include before exporting.

• Checkbox per endpoint in the map view
• "Select all" / "Deselect all" controls
• Export only operates on the selected set

Done when the user can choose a subset of endpoints and export only those.