feat(coder): persist token breakdown in arena decisions and schema

apps/coder/src/services/arena-decisions.ts

@@ -9,7 +9,7 @@
  * A contestant's status lifecycle:
  *   queued → running → done | error
  */
-import type { BattleType, ContestantLane } from '@boocode/contracts/arena';
+import type { BattleType, ContestantLane, TokenBreakdown } from '@boocode/contracts/arena';
 
 // ─── Lane classification ──────────────────────────────────────────────────────
 
@@ -73,6 +73,7 @@ export function isBattleComplete(contestants: readonly { status: string }[]): bo
 export interface Benchmark {
   durationMs: number;
   tokensPerSec: number | null;
+  tokenBreakdown: TokenBreakdown | null;
 }
 
 /**
@@ -86,13 +87,14 @@ export function computeBenchmark(
   endedAt: Date,
   costTokens: number | null,
   lane: ContestantLane,
+  tokenBreakdown: TokenBreakdown | null = null,
 ): Benchmark {
   const durationMs = Math.max(0, endedAt.getTime() - startedAt.getTime());
   const tokensPerSec =
     lane === 'local' && costTokens !== null && durationMs > 0
       ? (costTokens / durationMs) * 1000
       : null;
-  return { durationMs, tokensPerSec };
+  return { durationMs, tokensPerSec, tokenBreakdown };
 }
 
 // ─── Slug / path helpers ──────────────────────────────────────────────────────