fix(tokens): correct offlineAccent to the proposal's specified #E8879A

WU1's commit invented an arbitrary value for offlineAccent instead of using
the exact hex the proposal's WU1 scope line already specifies. listSurface
and liveGreen were correctly de-literalised from existing theme.dart
literals; offlineAccent has no prior literal, but its value is still not
this file's discretion — the proposal states #E8879A explicitly.

lib/tema/pluriwave_tokens.dart

@@ -41,8 +41,9 @@ class PluriWaveTokens extends ThemeExtension<PluriWaveTokens> {
   /// literal — same value, now named.
   final Color liveGreen;
 
-  /// Offline/reconnect banner accent (WU16). No prior literal to promote —
-  /// a genuinely new colour.
+  /// Offline/reconnect banner accent (WU16). Value from the proposal's WU1
+  /// scope line (`#E8879A`) — no prior literal in `pluriwave_theme.dart` to
+  /// promote, but the hex value itself is not this file's discretion.
   final Color offlineAccent;
 
   final double radiusSm;
@@ -73,7 +74,7 @@ class PluriWaveTokens extends ThemeExtension<PluriWaveTokens> {
     glowColor: Color(0x6621D4D9),
     listSurface: Color(0xFF102532),
     liveGreen: Color(0xFF7EE4C2),
-    offlineAccent: Color(0xFF94A3B8),
+    offlineAccent: Color(0xFFE8879A),
     radiusSm: 14,
     radiusMd: 22,
     radiusLg: 30,

test/tema/pluriwave_tokens_test.dart

@@ -27,8 +27,8 @@ void main() {
       },
     );
 
-    test('dark exposes offlineAccent as a genuinely new colour', () {
-      expect(PluriWaveTokens.dark.offlineAccent, const Color(0xFF94A3B8));
+    test('dark exposes offlineAccent per the proposal (#E8879A)', () {
+      expect(PluriWaveTokens.dark.offlineAccent, const Color(0xFFE8879A));
     });
 
     test('copyWith overrides only the new colour fields', () {