fix(dev): clear proxy env vars before launching backend

The opencode shell wrapper sets HTTPS_PROXY for z.ai API egress, and
child processes inherit it. The proxy rejects local IPs with 403,
breaking Proxmox API calls from the backend. Explicitly clear all
proxy env vars so the backend always talks direct to local infra.

scripts/hot-dev.sh

@@ -514,6 +514,8 @@ start_backend_process() {
     ALLOWED_ORIGINS="${ALLOWED_ORIGINS:-}" \
     LOG_FILE="${BACKEND_DEBUG_LOG}" \
     LOG_MAX_SIZE="50" \
+    HTTP_PROXY="" HTTPS_PROXY="" http_proxy="" https_proxy="" \
+    NO_PROXY="" no_proxy="" \
     ./pulse </dev/null >> "${BACKEND_DEBUG_LOG}" 2>&1 &
     STARTED_BACKEND_PID=$!
 }