refactor: consolidate duplicate toNumber into utils.ts, remove usage/shared.ts

usage/openai-codex.ts

@@ -10,8 +10,7 @@ import type {
   UsageReport,
   UsageWindow,
 } from "../usage";
-import { isRecord } from "../utils";
-import { toNumber } from "./shared";
+import { isRecord, toNumber } from "../utils";
 
 const CODEX_USAGE_PATH = "wham/usage";
 const JWT_AUTH_CLAIM = "https://api.openai.com/auth";

usage/shared.ts

@@ -1,10 +0,0 @@
-export const toNumber = (value: unknown): number | undefined => {
-  if (typeof value === "number" && Number.isFinite(value)) return value;
-  if (typeof value === "string") {
-    const trimmed = value.trim();
-    if (!trimmed) return undefined;
-    const parsed = Number(trimmed);
-    if (Number.isFinite(parsed)) return parsed;
-  }
-  return undefined;
-};