tweak color picking algorithm for power levels, and introduce setting for per PL or per user colors

lib/controllers/settings_sections.dart

@@ -19,6 +19,7 @@ import "package:nexus/controllers/unified_push_distributors.dart";
 import "package:nexus/helpers/extensions/distributor_name.dart";
 import "package:nexus/models/account_data.dart";
 import "package:nexus/models/client_state.dart";
+import "package:nexus/models/name_color.dart";
 import "package:nexus/models/room_order.dart";
 import "package:nexus/models/settings.dart";
 import "package:nexus/models/settings_category.dart";
@@ -83,6 +84,26 @@ class SettingsSectionsController
                     .onError(showError),
               ),
             ),
+            .new(
+              title: "Name Colors",
+              description: "Color names by power level, so moderators and admins stand out, or by user, so everyone has their own.",
+              icon: Icons.format_color_text,
+              builder: (title, description, icon) => DialogListTile<NameColor>(
+                icon: Icon(icon),
+                title: title,
+                subtitle: Text(description),
+                value: settings.nameColor,
+                options: NameColor.values,
+                getName: (option) => switch (option) {
+                  .powerLevel => "By power level",
+                  .user => "By user",
+                },
+                onChanged: (value) => ref
+                    .read(SettingsController.provider.notifier)
+                    .set(settings.copyWith(nameColor: value))
+                    .onError(showError),
+              ),
+            ),
             .new(
               title: "Use Dynamic Theme",
               icon: Icons.palette,

lib/helpers/extensions/displayname_color.dart

@@ -1,13 +1,29 @@
 import "package:flutter_riverpod/flutter_riverpod.dart";
 import "package:material_ui/material_ui.dart";
 import "package:nexus/controllers/room_power_levels.dart";
+import "package:nexus/controllers/settings.dart";
 import "package:nexus/helpers/extensions/string_to_color.dart";
 
 extension DisplaynameColor on WidgetRef {
-  /// The color of [userId]'s name in [roomId], hashed from their power level,
-  /// so everyone with the same level shares one.
-  Color displaynameColor(String roomId, String userId) => watch(
+  /// The color of [userId]'s name in [roomId], from their power level
+  /// (so everyone with the same level shares one) or their user ID, depending
+  /// on the user's settings.
+  Color displaynameColor(String roomId, String userId) => switch (watch(
+    SettingsController.provider.select((settings) => settings.value?.nameColor),
+  )) {
+    .user => userId.colorHash,
+    .powerLevel || null => powerLevelColor(
+      watch(
         RoomPowerLevelsController.provider(roomId)
             .select((levels) => levels.levelOf(userId)),
-  ).toString().colorHash;
+      ),
+    ),
+  };
+
+  static Color powerLevelColor(double level) => HSLColor.fromAHSL(
+    1,
+    level.isInfinite ? 30 : (210 + level / 50 * 137.50776) % 360,
+    0.7,
+    0.5,
+  ).toColor();
 }

lib/models/name_color.dart

@@ -0,0 +1,2 @@
+/// What users' name colors are hashed from.
+enum NameColor { powerLevel, user }

lib/models/settings.dart

@@ -1,5 +1,6 @@
 import "package:material_ui/material_ui.dart";
 import "package:freezed_annotation/freezed_annotation.dart";
+import "package:nexus/models/name_color.dart";
 import "package:nexus/models/room_order.dart";
 import "package:nexus/models/show_and_send.dart";
 
@@ -17,6 +18,7 @@ class const Settings({
   final bool swipeToReply = false,
   final bool hideMembershipEvents = false,
   final RoomOrder roomOrder = .unreadFirst,
+  final NameColor nameColor = .powerLevel,
   final ShowAndSend typingIndicators = .showAndSend,
 
   /// When not sending, read receipts are still sent privately, so that the