feat: add hytale-presskit module for Creator Presskit tracking

Adds new module to track CreatorPressKit.zip file size changes via HEAD requests.
Alerts with old/new size and diff. Also updates sign-token.ts with correct account ID.

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

src/modules/hytale-presskit/tracker.ts

@@ -0,0 +1,46 @@
+import type { StateStore } from '../../core/state-store.js'
+
+export interface PresskitUpdate {
+  size: number
+  previousSize: number | null
+  sizeDiff: number
+  date: string
+}
+
+const ENDPOINT = 'https://cdn.hytale.com/CreatorPressKit.zip'
+const STATE_KEY = 'hytale-presskit'
+
+export async function checkPresskitUpdate(stateStore: StateStore): Promise<PresskitUpdate | null> {
+  const response = await fetch(ENDPOINT, { method: 'HEAD' })
+  if (!response.ok) {
+    throw new Error(`Presskit endpoint returned ${response.status}`)
+  }
+
+  const contentLength = response.headers.get('content-length')
+  const date = response.headers.get('date')
+
+  if (!contentLength) {
+    throw new Error('Content-Length header missing')
+  }
+
+  const size = parseInt(contentLength, 10)
+
+  const state = stateStore.get<{ lastSize?: number, lastDate?: string }>(STATE_KEY)
+  const lastSize = state?.lastSize ?? null
+
+  if (lastSize === size) {
+    // No update, just update check time
+    stateStore.set(STATE_KEY, { lastSize: size, lastDate: date || new Date().toISOString() })
+    return null
+  }
+
+  // Update detected
+  stateStore.set(STATE_KEY, { lastSize: size, lastDate: date || new Date().toISOString() })
+
+  return {
+    size,
+    previousSize: lastSize,
+    sizeDiff: lastSize !== null ? size - lastSize : 0,
+    date: date || new Date().toISOString(),
+  }
+}