Turns live sessions into the airspace scan: each worktree session's git diff
becomes its working set, the dependency graph is built over the touched files,
and scanAirspace() produces the TCAS advisories + 3D positions.
- scripts/lib/control-pane/proximity.js: sessionsToAgents() + buildProximitySnapshot();
default working-set source shells `git diff --name-only <base>...HEAD` per
worktree (injectable for tests, fails closed to []).
- state.js: opt-in `proximity` field on the snapshot (includeProximity flag) so
the default hot path stays fast (git diffs only run when requested).
- 4 integration tests (same-file editors -> resolution, later agent steers,
<2 participants -> no advisories, labels). Full suite 2873/2873; lint green.
Affaan Mustafa
7df803935a