fix(web): browser-safe ere computation

- Add byteLength helper (Buffer.byteLength or TextEncoder fallback)\n- Use in puid.ts and puid.web.ts to avoid Buffer dependency in browsers\n- All tests passing

Author: dingosky

src/lib/byteLength.ts

@@ -0,0 +1,7 @@
+export const byteLength = (s: string): number => {
+  const B: any = (globalThis as any)?.Buffer
+  if (B && typeof B.byteLength === 'function') return B.byteLength(s)
+  if (typeof TextEncoder !== 'undefined') return new TextEncoder().encode(s).length
+  // Fallback: UTF-16 code units length; acceptable as a last resort for ere
+  return s.length
+}

src/lib/puid.ts

@@ -5,6 +5,7 @@ import { EntropyByBytes, EntropyByValues, EntropyFunction, Puid, PuidConfig, Pui
 import muncher from './bits'
 import { Chars, charsName, validChars } from './chars'
 import { entropyBits, entropyBitsPerChar } from './entropy'
+import { byteLength } from './byteLength'
 
 const round2 = (f: number): number => round(f * 100) / 100
 
@@ -99,7 +100,7 @@ export default (puidConfig: PuidConfig = {}): PuidResult => {
       : puidConfig.bits || DEFAULT_ENTROPY
   const puidBitsPerChar = entropyBitsPerChar(puidChars)
   const puidLen = round(ceil(puidEntropyBits / puidBitsPerChar))
-  const ere = (puidBitsPerChar * puidChars.length) / (8 * Buffer.byteLength(puidChars))
+  const ere = (puidBitsPerChar * puidChars.length) / (8 * byteLength(puidChars))
 
   const bitsMuncher = muncher(puidLen, puidChars, selectEntropyFunction(puidConfig))
 

src/lib/puid.web.ts

@@ -3,6 +3,7 @@ import { EntropyByBytes, EntropyByValues, EntropyFunction, Puid, PuidConfig, Pui
 import muncher from './bits'
 import { Chars, charsName, validChars } from './chars'
 import { entropyBits, entropyBitsPerChar } from './entropy'
+import { byteLength } from './byteLength'
 
 const round2 = (f: number): number => round(f * 100) / 100
 
@@ -50,7 +51,7 @@ export default (puidConfig: PuidConfig = {}): PuidResult => {
       : puidConfig.bits || DEFAULT_ENTROPY
   const puidBitsPerChar = entropyBitsPerChar(puidChars)
   const puidLen = round(ceil(puidEntropyBits / puidBitsPerChar))
-  const ere = (puidBitsPerChar * puidChars.length) / (8 * Buffer.byteLength(puidChars))
+  const ere = (puidBitsPerChar * puidChars.length) / (8 * byteLength(puidChars))
 
   const bitsMuncher = muncher(puidLen, puidChars, selectEntropyFunction(puidConfig))