Q75: charts and billing use full-period statistics computed per org

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/shared/usage-stats.ts

@@ -0,0 +1,23 @@
+/** One org's period statistics: the last 7 local days, and the last 30 days of provider calls. */
+export interface UsageStatsRecord {
+  orgId: string;
+  days: Array<{
+    dayStart: string;
+    runs: number;
+    completedRuns: number;
+    failedRuns: number;
+    tokens: number;
+    callsWithoutUsage: number;
+  }>;
+  month: {
+    requests: number;
+    failures: number;
+    inputTokens: number;
+    cachedInputTokens: number;
+    outputTokens: number;
+    reasoningTokens: number;
+    callsWithoutUsage: number;
+  };
+  agentSpend: Array<{ agentId: string; requests: number; tokens: number; costCents: number }>;
+  providerActivity: Array<{ providerId: string; requests: number; failures: number }>;
+}