[Feature]: Life counter

[jcserv]

Problem

It'd be nice to have a life counter feature. Most life counters require an app download

Proposal

Add a frontend-only life counter section. Should contain the following features:

• commander damage

• counters

• configurable layouts, variable number of players,

• incr/decrement health

• set starting life

• choosing who goes first

• UX improvement: when marking commander damage, also simultaneously incr/decr the life total

Additional context

No response

[jcserv]

Context & pointers

This is frontend-only — no persistence needed (that's the whole pitch vs. app-store life counters; ours is just a web page). Keep it self-contained: no schema, no server actions.

Note the overlap with #23 (playtest) — both are browser-only game-state tools. Not a hard dependency, but if #23 lands a clean client-state pattern, reuse it. Keep the polish details from the proposal (e.g. commander-damage also decrementing life) — those are what make it feel finished.