fix(i18n): use each English locale's own dialect

en_US carried British spellings (favourites, catalogues) while en_GB
carried American ones (color). Each locale now uses its own throughout.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: sdornan

frontend/src/locales/en_GB/play.json

@@ -3,7 +3,7 @@
   "all-states": "All states",
   "back-to-gallery": "Back to gallery",
   "back-to-game-details": "Back to game details",
-  "background-color": "Background color",
+  "background-color": "Background colour",
   "change-save": "Change save",
   "change-state": "Change state",
   "clear-cache": "Clear EmulatorJS Cache",
@@ -25,7 +25,7 @@
   "resume-from-save": "Resume from save",
   "resume-from-state": "Resume from state",
   "save-and-quit": "Save and quit",
-  "select-background-color": "Select background color",
+  "select-background-color": "Select background colour",
   "select-save": "Select save",
   "select-state": "Select state",
   "show-bezel": "Show bezel",

frontend/src/locales/en_GB/settings.json

@@ -174,7 +174,7 @@
   "grant-none": "Not granted",
   "grant-own": "Own items only",
   "group-account": "Account",
-  "group-color": "Color",
+  "group-color": "Colour",
   "group-default-option": "Default group",
   "group-default-tag": "Default",
   "group-delete-confirm": "Delete the \"{name}\" group? Its members fall back to the default group.",

frontend/src/locales/en_US/rom.json

@@ -17,7 +17,7 @@
   "add-new-note": "Add New Note",
   "add-note": "Add Note",
   "add-to-collection": "Add to collection",
-  "add-to-favorites": "Add to favourites",
+  "add-to-favorites": "Add to favorites",
   "adding-to-collection": "Adding {n} ROMs to collection",
   "additional-content": "Additional content",
   "additional-details": "Additional details",
@@ -312,7 +312,7 @@
   "remove-cover": "Remove cover",
   "remove-favorite": "Remove favorite",
   "remove-from-collection": "Remove from collection",
-  "remove-from-favorites": "Remove from favourites",
+  "remove-from-favorites": "Remove from favorites",
   "remove-from-playing": "Remove from playing",
   "removing-from-collection": "Removing {n} ROMs from collection",
   "removing-title": "Removing {n} game from RomM | Removing {n} games from RomM",

frontend/src/locales/en_US/setup.json

@@ -30,7 +30,7 @@
   "loading-library": "Inspecting your library…",
   "loading-library-failed": "Failed to load library info",
   "metadata-catalogs": "General metadata",
-  "metadata-catalogs-hint": "First-party catalogues. RomM queries them directly with your API key.",
+  "metadata-catalogs-hint": "First-party catalogs. RomM queries them directly with your API key.",
   "metadata-missing": "API key missing or invalid",
   "metadata-proxies": "Match proxies",
   "metadata-proxies-hint": "Community-hosted matchers that improve hits using file hashes.",
@@ -66,7 +66,7 @@
   "provider-launchbox-desc": "Community metadata, cover art, and screenshots.",
   "provider-launchbox-setup": "Set LAUNCHBOX_API_ENABLED=true and ENABLE_SCHEDULED_UPDATE_LAUNCHBOX_METADATA=true.",
   "provider-moby-caveat": "The API is a paid feature.",
-  "provider-moby-desc": "Catalogue, alternate cover art, and screenshots.",
+  "provider-moby-desc": "Catalog, alternate cover art, and screenshots.",
   "provider-moby-setup": "Requires a MobyGames account. Set MOBYGAMES_API_KEY.",
   "provider-ra-caveat": "Requires file hashes. Enable hash calculation in the scan.",
   "provider-ra-desc": "Achievement progress and unlock data per user.",