fix: convert strings to Uint8Array for @noble/hashes v2

@noble/hashes v2 no longer accepts strings directly, only Uint8Array.
Added utf8() helper to encode strings before hashing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

convex/liveChat.ts

@@ -10,8 +10,10 @@ import { bytesToHex as toHex } from "@noble/hashes/utils.js"
 // HELPERS
 // ============================================
 
+const utf8 = (s: string) => new TextEncoder().encode(s)
+
 function hashToken(token: string) {
-  return toHex(sha256(token))
+  return toHex(sha256(utf8(token)))
 }
 
 async function validateMachineToken(

convex/machines.ts

@@ -92,6 +92,8 @@ function toHex(input: Uint8Array) {
     .join("")
 }
 
+const utf8 = (s: string) => new TextEncoder().encode(s)
+
 function computeFingerprint(tenantId: string, companySlug: string | undefined, hostname: string, ids: NormalizedIdentifiers) {
   const payload = JSON.stringify({
     tenantId,
@@ -100,7 +102,7 @@ function computeFingerprint(tenantId: string, companySlug: string | undefined, h
     macs: ids.macs,
     serials: ids.serials,
   })
-  return toHex(sha256(payload))
+  return toHex(sha256(utf8(payload)))
 }
 
 function generateManualFingerprint(tenantId: string, displayName: string) {
@@ -110,7 +112,7 @@ function generateManualFingerprint(tenantId: string, displayName: string) {
     nonce: toHex(randomBytes(16)),
     createdAt: Date.now(),
   })
-  return toHex(sha256(payload))
+  return toHex(sha256(utf8(payload)))
 }
 
 function formatDeviceCustomFieldDisplay(
@@ -180,7 +182,7 @@ function matchesExistingHardware(existing: Doc<"machines">, identifiers: Normali
 }
 
 function hashToken(token: string) {
-  return toHex(sha256(token))
+  return toHex(sha256(utf8(token)))
 }
 
 function getRemoteAccessTokenGraceMs() {

convex/usbPolicy.ts

@@ -11,8 +11,10 @@ function toHex(input: Uint8Array) {
     .join("")
 }
 
+const utf8 = (s: string) => new TextEncoder().encode(s)
+
 function hashToken(token: string) {
-  return toHex(sha256(token))
+  return toHex(sha256(utf8(token)))
 }
 
 export const USB_POLICY_VALUES = ["ALLOW", "BLOCK_ALL", "READONLY"] as const