feat: add utils.ts with formatDate and capitalize functions

- Add formatDate(date: Date): string function
- Add capitalize(str: string): string function
- Include JSDoc documentation

Closes #2

src/utils.ts

@@ -0,0 +1,27 @@
+/**
+ * Utility functions for common operations
+ */
+
+/**
+ * Formats a Date object to a readable string (YYYY-MM-DD)
+ * @param date - The date to format
+ * @returns Formatted date string
+ */
+export function formatDate(date: Date): string {
+    const year = date.getFullYear()
+    const month = String(date.getMonth() + 1).padStart(2, "0")
+    const day = String(date.getDate()).padStart(2, "0")
+    return `${year}-${month}-${day}`
+}
+
+/**
+ * Capitalizes the first letter of a string
+ * @param str - The string to capitalize
+ * @returns String with first letter capitalized
+ */
+export function capitalize(str: string): string {
+    if (str.length === 0) {
+        return str
+    }
+    return str.charAt(0).toUpperCase() + str.slice(1)
+}