feat: CDP_PROFILE_OVERRIDE env for per-source browser isolation

Pair with CDP_PORT_OVERRIDE so parallel harvests can each drive a
dedicated Chromium instance (own port + own user-data-dir).

skills/news-harvester/scripts/ensure-chromium.js

@@ -58,7 +58,7 @@ function resolveOptions(config, portOverride) {
   const chromium = (config && config.chromium) || {};
   const cdpPort = parseInt(portOverride || process.env.CDP_PORT_OVERRIDE || chromium.cdpPort || '9222', 10);
   const headless = chromium.headless !== false; // default true, set false to keep a window
-  const userDataDir = chromium.userDataDir || DEFAULT_PROFILE;
+  const userDataDir = process.env.CDP_PROFILE_OVERRIDE || chromium.userDataDir || DEFAULT_PROFILE;
   return { cdpPort, headless, userDataDir, executablePath: chromium.executablePath || null };
 }