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.

tests/test_env_check.py

@@ -217,6 +217,35 @@ class EnvCheckTest(unittest.TestCase):
         report = server.env_check()
         self.assertEqual(self.steps(report, 'wlan0mon hopping on')[0]['ok'], 'pass')
 
+    def test_sta_uplink_disabled_when_enabled(self):
+        self.safe_set()
+        self.uci_state['wireless.dummy_radio0.mode'] = 'sta'
+        self.uci_state['wireless.dummy_radio0.ifname'] = 'wlan0'
+        self.uci_state['wireless.dummy_radio0.disabled'] = '0'
+        report = server.env_check()
+        self.assertEqual(self.steps(report, 'dummy_radio0 STA uplink disabled')[0]['ok'], 'fixed')
+        self.assertEqual(self.uci_state['wireless.dummy_radio0.disabled'], '1')
+        self.assertIn(['wifi', 'reload'], self.runs)
+
+    def test_sta_uplink_pass_when_absent(self):
+        self.safe_set()
+        report = server.env_check()
+        self.assertEqual(self.steps(report, 'no STA uplink pinning phy0')[0]['ok'], 'pass')
+
+    def test_sta_uplink_pass_when_disabled(self):
+        self.safe_set()
+        self.uci_state['wireless.dummy_radio0.mode'] = 'sta'
+        self.uci_state['wireless.dummy_radio0.disabled'] = '1'
+        report = server.env_check()
+        self.assertEqual(self.steps(report, 'no STA uplink pinning phy0')[0]['ok'], 'pass')
+
+    def test_recon_status_exposes_sta(self):
+        self.safe_set()
+        self.uci_state['wireless.dummy_radio0.mode'] = 'sta'
+        status, payload = server.h_recon_status(type('C', (), {'query': {}})())
+        self.assertEqual(status, 200)
+        self.assertTrue(payload['wlan0_sta'])
+
     def test_cli_exits_zero_on_pass(self):
         self.safe_set()
         buf = io.StringIO()