Standardize time formatting and avoid string slicing

- Created formatTimeString() utility to properly parse time strings
- Replaced all .slice(0, 5) calls with proper time formatting
- Handles both 'HH:MM:SS' and 'HH:MM' formats safely
- More robust than string slicing

frontend/app/utils/date.ts

@@ -46,6 +46,19 @@ export function formatDisplayDate(d: Date): string {
   return d.toLocaleDateString("en-US", { weekday: "short", month: "short", day: "numeric" });
 }
 
+/**
+ * Format time string from "HH:MM:SS" or "HH:MM" format to "HH:MM".
+ * Avoids string slicing by properly parsing the time.
+ */
+export function formatTimeString(timeStr: string): string {
+  // Handle both "HH:MM:SS" and "HH:MM" formats
+  const parts = timeStr.split(":");
+  if (parts.length >= 2) {
+    return `${parts[0].padStart(2, "0")}:${parts[1].padStart(2, "0")}`;
+  }
+  return timeStr;
+}
+
 /**
  * Get date range for booking/availability (from minAdvanceDays to maxAdvanceDays).
  * Returns an array of Date objects starting from minAdvanceDays days from today.