feat(debug): temporary BLE debug page for on-device verification

- entry in profile menu, visible only while a device is connected
- live FFE4 readout: 7x PD, VBAT, fitting, scan wave marker, run state
- tap a face-map region to fire a 2s single-region treat command
  (verifies region-to-IO mapping on the physical mask)
- wavelength selector (red/ir/uv/yellow) to verify color byte order
- scan command / full-face 2s / stop buttons, hex log of every write
- intentionally not i18n'd; remove page before release

miniprogram/app.json

@@ -20,7 +20,8 @@
     "pages/contact/contact",
     "pages/light-info/light-info",
     "pages/manual-treatment/manual-treatment",
-    "pages/scan-report/scan-report"
+    "pages/scan-report/scan-report",
+    "pages/ble-debug/ble-debug"
   ],
   "window": {
     "navigationBarBackgroundColor": "#ffffff",
@@ -65,4 +66,4 @@
   ],
   "style": "v2",
   "sitemapLocation": "sitemap.json"
-}
+}