refactor: convert to modular system with Hytale update trackers

- Core infrastructure: module interface, Telegram wrapper, OAuth token manager, state store
- Migrate Discord forwarder to modules/discord-forwarder/
- Add Hytale update trackers: launcher, patches, downloader, server
- Support multiple Telegram chats with per-chat topic IDs
- Unified config with legacy migration and env var fallbacks
- Auto-refresh OAuth tokens (5min buffer)

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

src/core/state-store.ts

@@ -0,0 +1,84 @@
+import fs from 'node:fs/promises'
+
+const STATE_FILE = './state.json'
+const DEBOUNCE_MS = 5000
+
+export class StateStore {
+  private state = new Map<string, unknown>()
+  private dirty = new Set<string>()
+  private persistTimer: NodeJS.Timeout | null = null
+  private loaded = false
+
+  async load(): Promise<void> {
+    if (this.loaded) {
+      return
+    }
+
+    try {
+      const content = await fs.readFile(STATE_FILE, 'utf-8')
+      const data = JSON.parse(content) as Record<string, unknown>
+
+      for (const [key, value] of Object.entries(data)) {
+        this.state.set(key, value)
+      }
+    }
+    catch (err) {
+      if ((err as NodeJS.ErrnoException).code !== 'ENOENT') {
+        console.warn('[StateStore] Failed to load state file:', err)
+      }
+    }
+
+    this.loaded = true
+  }
+
+  get<T>(key: string): T | undefined {
+    return this.state.get(key) as T
+  }
+
+  set<T>(key: string, value: T): void {
+    this.state.set(key, value)
+    this.dirty.add(key)
+    this.schedulePersist()
+  }
+
+  private schedulePersist(): void {
+    if (this.persistTimer) {
+      return
+    }
+
+    this.persistTimer = setTimeout(() => {
+      this.persist().catch((err) => {
+        console.error('[StateStore] Failed to persist state:', err)
+      })
+    }, DEBOUNCE_MS)
+  }
+
+  private async persist(): Promise<void> {
+    this.persistTimer = null
+
+    if (this.dirty.size === 0) {
+      return
+    }
+
+    const toSave: Record<string, unknown> = {}
+    for (const key of this.dirty) {
+      toSave[key] = this.state.get(key)
+    }
+
+    try {
+      await fs.writeFile(STATE_FILE, JSON.stringify(toSave, null, 2))
+      this.dirty.clear()
+    }
+    catch (err) {
+      console.error('[StateStore] Failed to write state file:', err)
+    }
+  }
+
+  async flush(): Promise<void> {
+    if (this.persistTimer) {
+      clearTimeout(this.persistTimer)
+      this.persistTimer = null
+    }
+    await this.persist()
+  }
+}