refactor(encoding): update character set

src/lib/constants.ts

···
 	/** Maximum collision resolution attempts */
 	MAX_COLLISION_ATTEMPTS: 20,
 
-	/** Base70 character set (includes special characters) */
-	BASE62_CHARS: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ+=_-?<>'
+	/** character set */
+	CHARS: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
 } as const;
 
 /**

src/lib/utils/encoding.ts

···
 import { SHORTCODE } from '$lib/constants';
 
 /**
- * Base70 characters used for encoding (0-9, a-z, A-Z, and special chars: +=_-?<>)
+ * characters used for encoding (0-9, a-z, A-Z)
  */
-const BASE_CHARS = SHORTCODE.BASE62_CHARS;
+const BASE_CHARS = SHORTCODE.CHARS;
 const BASE = BASE_CHARS.length;
 
 /**
···
  * Encodes a number to base string
  * @param num - Number to encode
  * @param length - Target length of the encoded string
- * @returns Base70 encoded string
+ * @returns encoded string
  */
 function toBase(num: number, length: number): string {
 	let encoded = '';
···
 }
 
 /**
- * Encodes a URL to a short base70 string
- * Uses a deterministic hash-to-base70 encoding
+ * Encodes a URL to a short string
+ * Uses a deterministic hash encoding
  *
  * @param url - URL to encode
  * @param length - Target length of the shortcode (default: 6)
- * @returns Short base70 encoded string
+ * @returns Short encoded string
  *
  * @example
  * encodeUrl('https://github.com/user') // Returns something like 'a3k9zx'
···
 }
 
 /**
- * Validates if a string is a valid base70 shortcode
+ * Validates if a string is a valid shortcode
  * @param code - String to validate
  * @returns True if the code contains only valid characters
  */
 export function isValidShortcode(code: string): boolean {
-	return /^[0-9a-zA-Z+=_\-?<>]+$/.test(code);
+	return /^[0-9a-zA-Z]+$/.test(code);
 }
 
 /**
···
  * @returns Number of possible combinations
  *
  * @example
- * getMaxCombinations(6) // Returns 117649000000 (70^6)
+ * getMaxCombinations(6)
  */
 export function getMaxCombinations(length: number): number {
 	return Math.pow(BASE, length);