fix: guard debug proxy CONNECT under managed proxy (#77010)

Summary:
- The PR adds a managed-proxy-aware debug proxy direct-upstream guard, a diagnostics override env var, regression tests, docs, and a changelog entry.
- Reproducibility: yes. Source inspection on current main shows direct HTTP forwarding and CONNECT net.connect() can run while managed proxy mode is active, against the documented managed-proxy egress guardrail.

Automerge notes:
- Ran the ClawSweeper repair loop before final review.
- Included post-review commit in the final squash: fix(clawsweeper): address review for automerge-openclaw-openclaw-7701…

Validation:
- ClawSweeper review passed for head aaa52a7f5f.
- Required merge gates passed before the squash merge.

Prepared head SHA: aaa52a7f5f
Review: https://github.com/openclaw/openclaw/pull/77010#issuecomment-4367600656

Co-authored-by: jesse-merhi <79823012+jesse-merhi@users.noreply.github.com>
Co-authored-by: clawsweeper <274271284+clawsweeper[bot]@users.noreply.github.com>

docs/security/network-proxy.md

@@ -194,6 +194,7 @@ proxy:
 - The proxy improves coverage for process-local JavaScript HTTP and WebSocket clients, but it is not an OS-level network sandbox.
 - Raw `net`, `tls`, and `http2` sockets, native addons, and child processes may bypass Node-level proxy routing unless they inherit and respect proxy environment variables.
 - IRC is a raw TCP/TLS channel outside operator-managed forward proxy routing. In deployments that require all egress through that forward proxy, set `channels.irc.enabled=false` unless direct IRC egress is explicitly approved.
+- The local debug proxy is diagnostic tooling and its direct upstream forwarding for proxy requests and CONNECT tunnels is disabled by default while managed proxy mode is active; enable direct forwarding only for approved local diagnostics.
 - User local WebUIs and local model servers should be allowlisted in the operator proxy policy when needed; OpenClaw does not expose a general local-network bypass for them.
 - Gateway control-plane proxy bypass is intentionally limited to `localhost` and literal loopback IP URLs. Use `ws://127.0.0.1:18789`, `ws://[::1]:18789`, or `ws://localhost:18789` for local direct Gateway control-plane connections; other hostnames route like ordinary hostname-based traffic.
 - OpenClaw does not inspect, test, or certify your proxy policy.