- Replace flat planetDefenseBase (20) with proportional planetDefenseScale
(0.06), so colony defense damage scales purely with current defenseHp.
A near-depleted colony now barely scratches attackers, while a fully
tech'd one still tops out ~110 damage — fixing "attacked with the
strength of a much-better-defended planet" (Brian, 2026-08-14).
- Add AI war memory: track consecutive losses per enemy and escalate
attackMultiplier up to 3x so repeated losing attacks stop dribbling
small fleets. A win resets the streak. Prevents permanent phoney wars
where both sides build to equal strength and nothing moves.
- Show "Under Attack" notice (one-button, no formation picker) when AI
attacks the player, since formation choice is meaningless for defense.
- Add planetary beam fire SFX for combat view.
- Add event `seq` cursor for war memory to survive event list trimming.
- Full test coverage for planet damage formula and AI escalation behavior.
