feat(ModularBot): pluggable bot with 4 guns, phantom meteor movement, radar harness

- Gun harness: virtual bullet tracker, rolling fitness, auto-selector
- Guns: head-on, linear (extrapolation), circular (integrated formula), tsetlin machine (learning)
- Movement: phantom meteor gravity engine (danger histograms, phantom bullets, fire detection)
- Radar: harness + radar_lock adapter
- Color-coded modules: turret/bullet color per gun, body per movement, scan per radar
- Beats Target, SpinBot, Crazy, TrackFire in 10-round battles

common_libs/radar_harness/radar_interface.nim

@@ -0,0 +1,15 @@
+## Radar harness — shared RadarModule concept.
+## Coordinate system: 0° = East, CCW positive (Tank Royale standard).
+
+import ../gun_harness/gun_interface
+
+export gun_interface  # re-export WorldState
+
+## Radar concept — any type T implementing computeScan is a valid radar module.
+template isRadarModule*(T: typedesc): bool =
+  compiles(
+    block:
+      var r: T
+      let ws = WorldState()
+      let rate: float = r.computeScan(ws)
+  )