gen5: record HELLO revision instead of gating parsing

lib/src/control.dart

@@ -414,16 +414,15 @@ class Gen5HelloInfo {
 
   /// Parse EXACTLY the response body (no header). Returns null when the body is
   /// shorter than the [semanticBodyLen] the fixed-offset parser needs — a short
-  /// body is a failed/foreign reply, never a partially-filled hello — or when
-  /// the body does not announce hello revision 1, since every offset below is
-  /// revision-1-specific and reading them out of an unknown revision would
-  /// invent an identity rather than decode one.
+  /// body is a failed/foreign reply, never a partially-filled hello. The
+  /// revision byte is recorded in [helloRevision] but is not a gate: the
+  /// official parser reads the fixed revision-1 offsets regardless of its
+  /// value.
   ///
   /// Callers should additionally gate on the command-response STATUS byte; a
   /// non-success reply leaves the body unpopulated (see [parseCommandResponse]).
   static Gen5HelloInfo? parse(Uint8List body) {
     if (body.length < semanticBodyLen) return null;
-    if (body[0] != 1) return null; // revision-1 map only
     String cstr(int start, int end) {
       final sb = StringBuffer();
       for (int i = start; i < end && i < body.length; i++) {

test/gen5_historical_test.dart

@@ -799,10 +799,17 @@ void main() {
       }
     });
 
-    test('an unknown hello revision is refused, not read at rev-1 offsets', () {
+    test('a non-1 hello revision still parses at the fixed offsets', () {
+      // The revision byte is recorded, not a gate — the official parser reads
+      // the fixed offsets regardless of its value.
       final body = gen5HelloBody();
       body[0] = 2; // some future revision
-      expect(Gen5HelloInfo.parse(body), isNull);
+      final h = Gen5HelloInfo.parse(body)!;
+      expect(h.helloRevision, 2);
+      expect(h.batteryPct, 90);
+      expect(h.serial, '5AG0000001');
+      expect(h.firmwareVersion, '50.40.1.0');
+      expect(h.wristOn, isTrue);
     });
 
     test('an out-of-range battery is omitted, never clamped', () {