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>

CLAUDE.md

@@ -12,34 +12,118 @@ npx eslint src/  # ESLint check
 
 ## Architecture
 
-Discord-to-Telegram message forwarder. Tracks messages from Discord servers and forwards them to Telegram topics.
+Modular notification system supporting Discord message forwarding and Hytale update tracking.
 
 ```
 src/
-├── index.ts              # Entry point, initializes clients
-├── env.ts                # Environment variables (DISCORD_TOKEN, TELEGRAM_BOT_TOKEN)
-├── config.ts             # Loads config.json, validates server/role/channel structure
+├── index.ts              # Module orchestrator entry point
+├── env.ts                # Environment variables
+├── config.ts             # Unified config loader with legacy migration
 ├── types.ts              # Shared TypeScript interfaces
-├── discord/
-│   ├── client.ts         # discord.js-selfbot-v13 client
-│   └── handlers.ts       # messageCreate handler, channel/role matching
-└── telegram/
-    ├── client.ts         # wrappergram client
-    └── sender.ts         # Message forwarding, media group handling
+│
+├── core/                 # Shared infrastructure
+│   ├── module.ts         # Module interface
+│   ├── telegram-client.ts # Telegram client wrapper
+│   ├── token-manager.ts  # OAuth token storage + auto-refresh
+│   └── state-store.ts    # Persistent state for trackers
+│
+└── modules/              # Pluggable modules
+    ├── discord-forwarder/ # Discord → Telegram message forwarding
+    ├── hytale-launcher/   # Launcher version tracker
+    ├── hytale-patches/    # Game patches tracker (auth:launcher)
+    ├── hytale-downloader/ # Downloader version tracker
+    └── hytale-server/     # Server software tracker (auth:downloader)
 ```
 
-**Flow**: Discord messageCreate → match by channel or role → forward to Telegram topic with attachments
+## Modules
 
-**Matching Priority**:
-1. Channels checked first (if configured)
-2. Roles checked second (highest priority role = first in config array)
+### Discord Forwarder
+Tracks Discord servers and forwards messages to Telegram topics based on channel/role matching.
 
-Servers can have `channels`, `roles`, or both. Channel matches skip role display in Telegram message.
+### Hytale Update Trackers
+- **hytale-launcher**: Polls `launcher.hytale.com/version/release/launcher.json` (no auth)
+- **hytale-patches**: Polls `account-data.hytale.com/my-account/get-launcher-data` (requires `auth:launcher` scope)
+- **hytale-downloader**: Polls `downloader.hytale.com/version.json` (no auth)
+- **hytale-server**: Two-step process via `account-data.hytale.com/game-assets/version/<patchline>.json` (requires `auth:downloader` scope)
 
 ## Config
 
-- `config.json` - Server/channel/role/topic mappings (see `config.json.example`)
-- `.env` - Tokens (see `.env.example`)
+### `.env`
+```
+DISCORD_TOKEN=your_discord_user_token
+TELEGRAM_BOT_TOKEN=your_telegram_bot_token
+```
+
+### `config.json`
+
+```json
+{
+  "telegram": { "botToken": "TELEGRAM_BOT_TOKEN" },
+  "modules": {
+    "discord-forwarder": {
+      "enabled": true,
+      "ignoredUserIds": [],
+      "chatId": "-100123456789",
+      "servers": [
+        {
+          "name": "Hytale",
+          "guildId": "123456789012345678",
+          "roles": [
+            { "id": "111111111111111111", "name": "Developer", "topicId": 5 }
+          ]
+        }
+      ]
+    },
+    "hytale-launcher": {
+      "enabled": true,
+      "pollIntervalMinutes": 5,
+      "chatIds": ["-100123456789"]
+    },
+    "hytale-patches": {
+      "enabled": true,
+      "pollIntervalMinutes": 5,
+      "chatIds": ["-100123456789"],
+      "patchlines": ["release", "pre-release"]
+    },
+    "hytale-downloader": {
+      "enabled": true,
+      "pollIntervalMinutes": 5,
+      "chatIds": ["-100123456789"]
+    },
+    "hytale-server": {
+      "enabled": true,
+      "pollIntervalMinutes": 5,
+      "chatIds": ["-100123456789"],
+      "patchlines": ["release", "pre-release"]
+    }
+  },
+  "hytaleAuth": {
+    "launcher": {
+      "clientId": "hytale-launcher",
+      "tokenFile": "./tokens/launcher.json"
+    },
+    "downloader": {
+      "clientId": "hytale-downloader",
+      "tokenFile": "./tokens/downloader.json"
+    }
+  }
+}
+```
+
+## Token Setup
+
+For authenticated endpoints (hytale-patches, hytale-server), create `tokens/*.json` files:
+
+```json
+{
+  "access_token": "...",
+  "refresh_token": "...",
+  "expires_at": 1737123456789,
+  "scope": "auth:launcher"
+}
+```
+
+Tokens are automatically refreshed before expiry (5min buffer).
 
 ## Code Style