live activity: tint pump glyph by monitored fuel

Move FuelType.tintColor (green=unleaded #30D158, yellow=premium #FFD60A,
cyan=diesel #64D2FF) into Shared/FuelStore.swift so the app, widget, and
Live Activity all read one definition (was app-only in StationsView, so the
widget couldn't see it). Tint the Live Activity rich card pump icon and the
Dynamic Island compactLeading pump by context.state.fuel.tintColor.

Shared/FuelStore.swift

@@ -8,6 +8,7 @@
 //   keychain → app-group defaults → fallback.
 
 import Foundation
+import SwiftUI
 import Security
 #if canImport(AppIntents)
 import AppIntents
@@ -99,6 +100,20 @@ enum FuelType: String, Codable, CaseIterable, Identifiable {
     }
 }
 
+/// Fuel colour wheel (user-chosen palette): green = unleaded (#30D158),
+/// yellow = premium (#FFD60A), cyan = diesel (#64D2FF). Lives here in Shared
+/// so the app, widget, and Live Activity all tint the pump/fuel glyphs from one
+/// definition.
+extension FuelType {
+    var tintColor: Color {
+        switch self {
+        case .e10: return Color(red: 48/255.0, green: 209/255.0, blue: 88/255.0)      // #30D158
+        case .e5: return Color(red: 255/255.0, green: 214/255.0, blue: 10/255.0)      // #FFD60A
+        case .diesel: return Color(red: 100/255.0, green: 210/255.0, blue: 255/255.0) // #64D2FF
+        }
+    }
+}
+
 #if canImport(AppIntents)
 extension FuelType: AppEnum {}
 #endif