feat(livestats): per-player killedBy + deathPosition + winner for live standings (#4593)

## Description:

Enriches the admin-bot live-stats snapshot
(`/api/adminbot/game/:id/stats`) with the per-player fields a semi-live
standings board needs, so it can score kills + placement live instead of
waiting for the post-game record.

Per player in `liveStats.players[]`:
- **`killedBy`** — the eliminator's clientID (null while alive /
non-client killer). Invert → live kill points.
- **`deathPosition`** — finishing place at elimination = non-bot players
still standing + 1 (frozen at "last of the then-standing"). Null while
alive → live placement.

The **full roster** is reported (dead players are retained in the client
view), plus top-level **`winner`** (the decided winner's clientID, else
null).

Deterministic / consensus-safe: `killedBy` (stamped at `recordKill`) and
`deathPosition` (stamped in `PlayerExecution`) are pure sim values, so
in-sync clients agree on the majority vote; `winner` is added
server-side in `GameServer.liveStats()` from the winner vote (like the
existing publicID/username/connected enrichment).

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory

src/core/StatsSchemas.ts

@@ -108,6 +108,11 @@ export const PlayerStatsSchema = z
     attacks: AtLeastOneNumberSchema.optional(),
     betrayals: BigIntStringSchema.optional(),
     killedAt: BigIntStringSchema.optional(),
+    // OFM live standings: the eliminator's clientID (null = eliminated by a
+    // non-client, e.g. a bot/nation) and finishing place at elimination. Both
+    // first-write-wins. Surfaced live on the PlayerUpdate (not just at game end).
+    killedBy: z.string().nullable().optional(),
+    deathPosition: z.number().optional(),
     // Tiles owned at game end, for OFM standings (set on setWinner).
     finalTiles: BigIntStringSchema.optional(),
     // Humans this player eliminated (victim clientID + tick), for OFM kill scoring.