## Flee Threshold Changes
- Reduced flee threshold from AttackRadius2+4 to AttackRadius2 (no buffer)
- Modified bots: farmer, gatherer, siege
- Bots now only consider enemies in actual attack range, not preemptively
- Added outnumber logic: only flee when nearbyAllies < nearbyEnemies
## Behavior Vector Changes
- Derive aggression from actual kill rate (not self-reported)
- Formula: behaviorVec[0] = min(killRate, 1.0)
- Preserves existing economy value or defaults to 0.5
- Enhanced logging to show derived aggression value
## Rationale
Aggression must be economically necessary, not just rewarded.
Previous flee logic created a false safe option that discouraged combat.
Now bots only flee when actually outnumbered within combat range.
Related: bf-413 genesis bead tracking mechanics iteration
- Add SiegeBot to engine/bot_strategies.go with spawn denial logic
- Implement standalone siege bot in bots/siege/ with main.go, strategy.go, Dockerfile
- Register siege bot in acb-local for arena testing
- Add test-siege-arena.sh script for validation
Strategy: Surround enemy cores to block spawning phase. Bot assigns
units to lockout rings (8 neighbors) around cores, greedily by distance.
Unassigned units collect energy or rush fully-sieged cores.
Tested: 3/10 wins vs rusher+gatherer, 1/10 wins vs rusher+gatherer+guardian
