build(docker): keep keys out of the image and run as non-root by default

The build context excluded only .env, so .env.local and the like or
pinokio/ENVIRONMENT would be baked into image layers; exclude every dotenv
file except .env.example, plus local state and QA output. Pin the base to
CI's Node 24.14.0 by digest, default to the image's node user, and correct
the HOST comment. Log the trusted peers as the operator's when set. README
notes that MCP and ChatGPT sign-in voice are unavailable under Docker, and
how to trust no gateway when widening the publish.

scripts/docker-start.mjs

@@ -105,12 +105,19 @@ async function start() {
     );
   }
 
+  const fromOperator = Boolean(
+    String(process.env.GEV_KEY_SETUP_TRUSTED_PEERS ?? '').trim(),
+  );
   const trustedPeers = resolveTrustedPeers({ routeTable: readRouteTable() });
   if (trustedPeers) {
     // Set before Vite is imported: the dev server snapshots process.env during
     // configuration, and the admission gate reads it per request.
     process.env.GEV_KEY_SETUP_TRUSTED_PEERS = trustedPeers;
-    console.log(`[Docker] Provider Settings trusts the container gateway (${trustedPeers}).`);
+    console.log(
+      fromOperator
+        ? `[Docker] Provider Settings trusted peers: ${trustedPeers} (GEV_KEY_SETUP_TRUSTED_PEERS).`
+        : `[Docker] Provider Settings trusts the container gateway (${trustedPeers}).`,
+    );
   } else {
     console.log('[Docker] No default gateway; Provider Settings stays loopback-only.');
   }