fix: write DNS results to /etc/hosts for undici/fetch compatibility

Telegram's grammY library uses undici (Node 22 built-in fetch) which
bypasses dns.lookup monkey-patching. Writing resolved IPs to /etc/hosts
ensures all DNS clients (including undici) can reach api.telegram.org.

Also chmod 666 /etc/hosts in Dockerfile so the node user can write to it.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -14,6 +14,7 @@ RUN echo "[build][layer1] System deps + tools..." && START=$(date +%s) \
   && chown node:node /app \
   && mkdir -p /home/node/.openclaw/workspace /home/node/.openclaw/credentials \
   && chown -R node:node /home/node \
+  && chmod 666 /etc/hosts \
   && echo "[build][layer1] System deps + tools: $(($(date +%s) - START))s"
 
 # ── 切换到 node 用户（后续所有操作都以 node 身份，无需 chown）───────────────

scripts/dns-resolve.py

@@ -94,6 +94,17 @@ def main() -> None:
     with open(output_file, "w") as f:
         json.dump(results, f, indent=2)
 
+    # Also write to /etc/hosts so undici/fetch (which bypasses dns.lookup) works
+    if results:
+        try:
+            with open("/etc/hosts", "a") as f:
+                f.write("\n# === HuggingClaw DoH resolved domains ===\n")
+                for domain, ip in results.items():
+                    f.write(f"{ip} {domain}\n")
+            print(f"[dns] Wrote {len(results)} entries to /etc/hosts")
+        except PermissionError:
+            print("[dns] WARNING: cannot write /etc/hosts (permission denied)")
+
     print(f"[dns] Resolved {len(results)}/{len(DOMAINS)} domains -> {output_file}")