feat: support FFE4 19-byte format with fitting and run_state fields

Per 协议简述(3): FFE4 now 19 bytes — adds Byte17 fitting status
(0=not fitted, 1=fitted) and Byte18 run state (0=IDLE, 1=scanning,
2=treating, FF=fault). Maintains backward compat with 17-byte format.

miniprogram/services/ble/protocol.js

@@ -199,6 +199,23 @@ function parseVendorStatus(buffer) {
   if (bytes.length === 1) {
     return { type: 'heartbeat', heartbeat: bytes[0], is_heartbeat: true, raw_hex: bytesToHex(bytes) }
   }
+  if (bytes.length === 19) {
+    var checksum19 = xorChecksum(bytes.slice(0, 18))
+    var pds19 = []
+    for (var p = 0; p < 7; p++) {
+      pds19.push(bytes[p * 2] | (bytes[p * 2 + 1] << 8))
+    }
+    return {
+      type: 'adc',
+      is_heartbeat: false,
+      pd: pds19,
+      vbat: bytes[14] | (bytes[15] << 8),
+      fitting: bytes[16],
+      run_state: bytes[17],
+      checksum_ok: checksum19 === bytes[18],
+      raw_hex: bytesToHex(bytes)
+    }
+  }
   if (bytes.length === 17) {
     var checksum = xorChecksum(bytes.slice(0, 16))
     var pds = []
@@ -210,6 +227,8 @@ function parseVendorStatus(buffer) {
       is_heartbeat: false,
       pd: pds,
       vbat: bytes[14] | (bytes[15] << 8),
+      fitting: -1,
+      run_state: -1,
       checksum_ok: checksum === bytes[16],
       raw_hex: bytesToHex(bytes)
     }