Add a reusable Important information disclaimer sheet

One sheet, reachable from the bottom of the Key sheet and from the bottom
of Settings, with each topic as its own card and heading:

- Fuel Prices, Fuel Availability, Savings & Best Value, Journey Estimates,
  Before You Travel and Disclaimer, in that order.
- Every heading carries an SF Symbol in a fixed-width, Dynamic-Type-aware
  slot, so heading text lines up across sections regardless of glyph width.
  Icons take the accent colour, headings are semibold and primary, and each
  description sits beneath its heading in secondary text.
- All copy lives in en.lproj/Localizable.strings keyed by the English
  literal, ready for the web copy editor.
- The sheet, its trigger row and the .importantInformationSheet(isPresented:)
  modifier live in one file, so any further entry point is a one-line change
  and the wording cannot drift between them.
- DEBUG-only `-showImportantInfo` launch hook, chained behind the Key sheet,
  for screenshotting without a tap.

FuelBoard/StationsView.swift

@@ -39,6 +39,11 @@ struct StationsView: View {
     /// the Key sheet and from the More info sheet.
     @State private var showBestValueInfo = false
 
+    /// The shared "Important information" disclaimer sheet. It lives at the
+    /// bottom of the Key sheet here; the same sheet is reused wherever else the
+    /// disclaimer is needed.
+    @State private var showImportantInformation = false
+
     /// Station picked for the More-info sheet (tap action = showDetails).
     @State private var detailStation: FuelStation?
 
@@ -223,6 +228,17 @@ struct StationsView: View {
                         showBestValueInfo = true
                     }
                 }
+                // QA hook: `-showImportantInfo` opens the Key sheet and then the
+                // shared disclaimer on top of it, so the copy can be
+                // screenshotted without a tap. Same chained requirement as
+                // `-showBestValueInfo` above.
+                if ImportantInformationQA.isRequested {
+                    showKey = true
+                    Task { @MainActor in
+                        try? await Task.sleep(nanoseconds: 1_200_000_000)
+                        showImportantInformation = true
+                    }
+                }
 #endif
             }
             .onReceive(NotificationCenter.default.publisher(for: .fuelBoardOpenBestValueSettings)) { _ in
@@ -348,6 +364,10 @@ struct StationsView: View {
                                 HowBestValueRow { showBestValueInfo = true }
                             }
                         }
+
+                        Section {
+                            ImportantInformationRow { showImportantInformation = true }
+                        }
                     }
                     .navigationTitle("Key")
                     .navigationBarTitleDisplayMode(.inline)
@@ -358,6 +378,8 @@ struct StationsView: View {
                     }
                     // Nested sheet: the Key sheet stays behind the explanation.
                     .sheet(isPresented: $showBestValueInfo) { HowBestValueSheet() }
+                    // Nested sheet: the Key sheet stays behind the disclaimer.
+                    .importantInformationSheet(isPresented: $showImportantInformation)
                 }
                 .presentationDetents([.fraction(0.6)])
                 .presentationBackground(Color(UIColor.systemGroupedBackground))