Add getLeaveStatus utility and update project status

- Introduce `getLeaveStatus` function in `packages/core/src/status-utils.ts` to determine leave-by status based on
  journey data
- Mark Phase 1 mobile app tasks as complete in `CHECKLIST.md`
- Add mobile workspace configurations and npm scripts

packages/core/src/status-utils.ts

@@ -1,5 +1,5 @@
 // Status utilities for TimeToLeave
-import type { ServerStatus } from "./types";
+import type { ServerStatus, Event, Journey } from "./types";
 
 export class StatusUtils {
   static async checkServerStatus(url: string): Promise<ServerStatus> {
@@ -14,3 +14,36 @@ export class StatusUtils {
     }
   }
 }
+
+/**
+ * Derive a human-readable leave-by status from an event and its journeys.
+ * Returns early / on-time / delayed / unknown based on the best journey's
+ * real departure time relative to now.
+ */
+export function getLeaveStatus(event: Event, journeys: Journey[]): string {
+  if (journeys.length === 0) {
+    return "No journey data";
+  }
+
+  // Pick the earliest non-cancelled journey
+  const best = journeys
+    .filter((j) => !j.cancelled)
+    .sort((a, b) => a.rD.getTime() - b.rD.getTime())[0];
+
+  if (!best) {
+    return "All journeys cancelled";
+  }
+
+  const diffMin = (best.rD.getTime() - Date.now()) / 60_000;
+
+  if (diffMin < 0) {
+    return "Departure missed";
+  }
+  if (best.delay > 10) {
+    return `Delayed +${best.delay} min`;
+  }
+  if (diffMin <= 15) {
+    return "Leave now";
+  }
+  return "On time";
+}