docs: update .env.example with modern channel examples

- Add examples for Telegram, Discord, Slack (current primary channels)
- Add examples for AI providers (Anthropic, OpenAI, Gemini)
- Add examples for optional services (Brave Search, ElevenLabs)
- Mark legacy Twilio config as deprecated
- Add helpful comments and links to get API keys

This makes it much easier for new users to understand what
environment variables are available and how to configure them.

.env.example

@@ -1,5 +1,57 @@
-# Copy to .env and fill with your Twilio credentials
-TWILIO_ACCOUNT_SID=ACxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
-TWILIO_AUTH_TOKEN=your_auth_token_here
-# Must be a WhatsApp-enabled Twilio number, prefixed with whatsapp:
-TWILIO_WHATSAPP_FROM=whatsapp:+17343367101
+# Moltbot Environment Variables Example
+# Copy this file to .env and fill in your credentials
+# Most settings can also be configured in ~/.clawdbot/moltbot.json
+
+# =============================================================================
+# CHANNELS - Configure your messaging platforms
+# =============================================================================
+
+# Telegram Bot
+# Get your bot token from @BotFather on Telegram
+TELEGRAM_BOT_TOKEN=your_telegram_bot_token_here
+
+# Discord Bot
+# Create a bot at https://discord.com/developers/applications
+DISCORD_BOT_TOKEN=your_discord_bot_token_here
+
+# Slack Bot (requires both tokens)
+# Create a Slack app at https://api.slack.com/apps
+SLACK_BOT_TOKEN=your_slack_bot_token_here
+SLACK_APP_TOKEN=your_slack_app_token_here
+
+# =============================================================================
+# AI MODEL PROVIDERS - API keys for AI capabilities
+# =============================================================================
+
+# Anthropic (Claude) - Recommended primary model
+# Get your API key from https://console.anthropic.com/
+ANTHROPIC_API_KEY=your_anthropic_api_key_here
+
+# OpenAI (GPT, DALL-E, Whisper)
+# Get your API key from https://platform.openai.com/api-keys
+OPENAI_API_KEY=your_openai_api_key_here
+
+# Google Gemini (optional)
+# Get your API key from https://aistudio.google.com/apikey
+GEMINI_API_KEY=your_gemini_api_key_here
+
+# =============================================================================
+# OPTIONAL SERVICES
+# =============================================================================
+
+# Brave Search (for web search capabilities)
+# Get your API key from https://brave.com/search/api/
+BRAVE_API_KEY=your_brave_api_key_here
+
+# ElevenLabs (for voice/TTS features)
+# Get your API key from https://elevenlabs.io/
+ELEVENLABS_API_KEY=your_elevenlabs_api_key_here
+
+# =============================================================================
+# LEGACY / DEPRECATED
+# =============================================================================
+
+# Twilio (legacy WhatsApp integration - consider using Baileys instead)
+# TWILIO_ACCOUNT_SID=ACxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+# TWILIO_AUTH_TOKEN=your_auth_token_here
+# TWILIO_WHATSAPP_FROM=whatsapp:+17343367101