docs: clarify Signal setup and env-token gating

CHANGELOG.md

@@ -13,6 +13,7 @@
   - new optional bundled allowlist: `skills.allowBundled` (only affects bundled skills)
 - Sessions: group keys now use `surface:group:<id>` / `surface:channel:<id>`; legacy `group:*` keys migrate on next message; `groupdm` keys are no longer recognized.
 - Discord: remove legacy `discord.allowFrom`, `discord.guildAllowFrom`, and `discord.requireMention`; use `discord.dm` + `discord.guilds`.
+- Providers: Discord/Telegram no longer auto-start from env tokens alone; add `discord: { enabled: true }` / `telegram: { enabled: true }` to your config when using `DISCORD_BOT_TOKEN` / `TELEGRAM_BOT_TOKEN`.
 
 ### Features
 - Talk mode: continuous speech conversations (macOS/iOS/Android) with ElevenLabs TTS, reply directives, and optional interrupt-on-speech.
@@ -48,6 +49,7 @@
 - Gateway CLI: read `CLAWDIS_GATEWAY_PASSWORD` from environment in `callGateway()` — allows `doctor`/`health` commands to auth without explicit `--password` flag.
 - Auto-reply: strip stray leading/trailing `HEARTBEAT_OK` from normal replies; drop short (≤ 30 chars) heartbeat acks.
 - Logging: trim provider prefix duplication in Discord/Signal/Telegram runtime log lines.
+- Logging/Signal: treat signal-cli "Failed …" lines as errors in gateway logs.
 - Discord: include recent guild context when replying to mentions and add `discord.historyLimit` to tune how many messages are captured.
 - Discord: include author tag + id in group context `[from:]` lines for ping-ready replies (thanks @thewilloftheshadow).
 - Gateway: fix TypeScript build by aligning hook mapping `channel` types and removing a dead Group DM branch in Discord monitor.