Convert a Column Number to an Excel-Style Label

Write a function column_label(n: int) -> str that translates a column number n into its Excel-style label. The columns are labeled with uppercase letters in a bijective base‑26 system: 1 → "A", 2 → "B", …, 26 → "Z". After Z, the labels continue as "AA", "AB", …, "AZ", "BA", and so forth. For this exercise you only need to handle n up to 500, so the output will contain at most two characters.

• n is an integer with 1 <= n <= 500.
• Return only the column label string, without any row number.
• The numbering starts at 1; there is no column 0.
• You may assume the input is always valid.

Hint: the absence of a zero digit means you must shift the value before extracting each letter. Decrease the current number by 1, then use % 26 to pick the right character from A–Z.

Example 1:

Input: n = 26
Output: "Z"

Explanation: Column 26 is the last single‑letter column.

Example 2:

Input: n = 27
Output: "AA"

Explanation: After Z, column 27 becomes the first two‑letter label.

Example 3:

Input: n = 500
Output: "SF"

Explanation: S is the 19th letter (19 × 26 = 494) and F is the 6th letter, making 500 → "SF".

Constraints:

• 1 <= n <= 500
• The function must produce only uppercase letters.