feat(settings): add feature flag for dark mode

Because:

* dark mode needs to be feature flagged

This commit:

* adds feature flag for dark mode

Closes FXA-13025

Author: MagentaManifold

packages/fxa-content-server/server/config/local.json-dist

@@ -76,6 +76,9 @@
     "showLocaleToggle": true,
     "paymentsNextSubscriptionManagement": true
   },
+  "darkMode": {
+    "enabled": true
+  },
   "rolloutRates": {
     "keyStretchV2": 1,
     "generalizedReactApp": 0

packages/fxa-content-server/server/lib/beta-settings.js

@@ -124,6 +124,9 @@ const settingsConfig = {
     passkeysEnabled: config.get('featureFlags.passkeysEnabled'),
     passwordlessEnabled: config.get('featureFlags.passwordlessEnabled'),
   },
+  darkMode: {
+    enabled: config.get('darkMode.enabled'),
+  },
   nimbus: {
     enabled: config.get('nimbus.enabled'),
     preview: config.get('nimbus.preview'),

packages/fxa-content-server/server/lib/configuration.js

@@ -260,6 +260,14 @@ const conf = (module.exports = convict({
       env: 'PASSWORDLESS_SIGNUP_ENABLED',
     },
   },
+  darkMode: {
+    enabled: {
+      default: false,
+      doc: 'Enables dark mode toggle',
+      format: Boolean,
+      env: 'DARK_MODE_ENABLED',
+    },
+  },
   cms: {
     enabled: {
       default: false,

packages/fxa-content-server/server/lib/routes/react-app/route-definition-index.js

@@ -58,6 +58,7 @@ function getIndexRouteDefinition(config) {
   const FEATURE_FLAGS_PASSKEYS_ENABLED = config.get(
     'featureFlags.passkeysEnabled'
   );
+  const DARK_MODE_ENABLED = config.get('darkMode.enabled');
   const GLEAN_ENABLED = config.get('glean.enabled');
   const GLEAN_APPLICATION_ID = config.get('glean.applicationId');
   const GLEAN_UPLOAD_ENABLED = config.get('glean.uploadEnabled');
@@ -126,6 +127,9 @@ function getIndexRouteDefinition(config) {
       showLocaleToggle: FEATURE_FLAGS_SHOW_LOCALE_TOGGLE,
       passkeysEnabled: FEATURE_FLAGS_PASSKEYS_ENABLED,
     },
+    darkMode: {
+      enabled: DARK_MODE_ENABLED,
+    },
     cms: {
       enabled: CMS_ENABLED,
       l10nEnabled: CMS_L10N_ENABLED,

packages/fxa-settings/src/lib/config.ts

@@ -104,6 +104,9 @@ export interface Config {
     passkeysEnabled?: boolean;
     passwordlessEnabled?: boolean;
   };
+  darkMode?: {
+    enabled?: boolean;
+  };
   nimbus: {
     enabled: boolean;
     preview: boolean;
@@ -200,6 +203,9 @@ export function getDefault() {
       paymentsNextSubscriptionManagement: false,
       passwordlessEnabled: false,
     },
+    darkMode: {
+      enabled: false,
+    },
     cms: {
       enabled: false,
       l10nEnabled: false,
@@ -275,4 +281,4 @@ export function update(newData: { [key: string]: any }) {
 }
 
 const config: Config = getDefault();
-export default config;
+export default config;