Combat polish: dead-hero pickup fix, +1 energy pulse on mana regen, End Turn fills the gaps

Pickup on dead-hero cells works now. If a living hero was standing on the same cell as a downed hero, tapping that cell used to do nothing — the click resolved to the dead hero's slot and bailed. Now the tap resolves to the living hero so you can select them and keep planning.

Mana regen has a visible tell. At SIDE_END (end of each side's turn), heroes get +1 energy from regen — but until now there was no on-screen signal for that tick, just the energy number changing. Playback now shows a +1 energy stat pulse on each hero's stat block at that moment, so the source of the energy is legible.

End Turn no longer waits on missed planning. If you forgot to assign an action to one of your heroes, hitting End Turn now auto-fills any missing slots with Skip and proceeds. Previously the button felt unresponsive when any hero hadn't been touched.

Tutorial highlights now match the required action type — sparkle for one kind of cue, gold border for another — instead of using a single visual for every step. Cleaner read for first-time players.