feat: fix API Key authentication and payload alignment

- Update openclaw.plugin.json: replace challengeUuid with apiKey (optional)
- Fix tsconfig: use CommonJS module to avoid import.meta.url issues
- Fix plugin/index.ts: remove ESM-specific code, use __dirname
- Fix telemetry.mjs:
  - Add loadavg to os imports, remove require() call
  - Replace challengeUuid with apiKey in config
  - Update endpoint to heartbeat-v2
  - Add X-API-Key header when apiKey is configured
  - Fix payload field names: agents, load_avg (array), uptime_seconds
  - Change missing apiKey from error to warning

plugin/index.d.ts

@@ -0,0 +1,24 @@
+interface PluginConfig {
+    enabled?: boolean;
+    backendUrl?: string;
+    identifier?: string;
+    apiKey?: string;
+    reportIntervalSec?: number;
+    httpFallbackIntervalSec?: number;
+    logLevel?: 'debug' | 'info' | 'warn' | 'error';
+}
+interface PluginAPI {
+    logger: {
+        info: (...args: any[]) => void;
+        error: (...args: any[]) => void;
+        debug: (...args: any[]) => void;
+        warn: (...args: any[]) => void;
+    };
+    version?: string;
+    isRunning?: () => boolean;
+    on: (event: string, handler: () => void) => void;
+    registerTool: (factory: (ctx: any) => any) => void;
+}
+export default function register(api: PluginAPI, config: PluginConfig): void;
+export {};
+//# sourceMappingURL=index.d.ts.map