feat: env check auto-disables dummy_radio0 STA (2.4GHz recon root cause)

The stock STA client interface (wlan0) holds phy0's channel, pinning wlan0mon
so 2.4GHz recon captures nothing (verified: iw set channel -> Resource busy
until wlan0 is down). env_check now disables it (uci wireless.dummy_radio0
disabled=1 + wifi reload) at startup and /api/recon/status exposes wlan0_sta
so the recon page can warn if it regresses.

payload/user/remote_access/pager-webui/server.py

@@ -1359,6 +1359,7 @@ def h_recon_status(ctx):
                  'scanning': scanning, 'scan_remaining': remaining, 'stale': stale,
                  'hopper_online': _hopper_online(),
                  'wlan0_pinned': _wlan0_pinned(),
+                 'wlan0_sta': _sta_uplink_enabled(),
                  'wlan0_hopping': _wlan0_hopping(),
                  'history_reset': _recon_history_reset()}
 
@@ -3717,6 +3718,20 @@ def _wlan0_pinned():
     return False
 
 
+def _sta_uplink_enabled():
+    """True when the stock dummy_radio0 STA client interface is enabled. The
+    STA holds phy0's channel, which pins wlan0mon and starves 2.4GHz recon
+    entirely (iw set channel fails with Resource busy while it is up)."""
+    cfg = _uci_values('wireless.dummy_radio0') or {}
+    return cfg.get('mode') == 'sta' and cfg.get('disabled') != '1'
+
+
+def _disable_sta_uplink():
+    device_run(['uci', 'set', 'wireless.dummy_radio0.disabled=1'])
+    device_run(['uci', 'commit', 'wireless'])
+    device_run(['wifi', 'reload'], timeout=30)
+
+
 def _pineap_interfaces():
     """Runtime pineapd interface table from ``_pineap INTERFACE LIST``:
     {name: {'channels': int, 'bands': str, 'hop': str, 'pkts': int}}."""
@@ -3790,6 +3805,13 @@ def env_check():
     else:
         _env_step(report, 'warn', pool_detail)
 
+    if _sta_uplink_enabled():
+        _disable_sta_uplink()
+        _env_step(report, 'fixed', '2.4GHz recon: dummy_radio0 STA uplink disabled '
+                                  '(it was pinning phy0 so wlan0mon could not hop)')
+    else:
+        _env_step(report, 'pass', 'no STA uplink pinning phy0')
+
     raised = _raise_monitors()
     if raised:
         _env_step(report, 'fixed', 'monitor interfaces brought up', ', '.join(raised))