feat(telegram): add base_url support for custom Telegram Bot API server (#1021)

* feat(telegram): add base_url support for custom Telegram Bot API server

Allow users to specify a custom Telegram Bot API server URL via
config field `base_url` or env var `PICOCLAW_CHANNELS_TELEGRAM_BASE_URL`.
Defaults to the official https://api.telegram.org when left empty.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(telegram): trim whitespace and trailing slash from base_url

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

config/config.example.json

@@ -49,6 +49,7 @@
     "telegram": {
       "enabled": false,
       "token": "YOUR_TELEGRAM_BOT_TOKEN",
+      "base_url": "",
       "proxy": "",
       "allow_from": [
         "YOUR_USER_ID"

pkg/channels/telegram/telegram.go

@@ -72,6 +72,10 @@ func NewTelegramChannel(cfg *config.Config, bus *bus.MessageBus) (*TelegramChann
 		}))
 	}
 
+	if baseURL := strings.TrimRight(strings.TrimSpace(telegramCfg.BaseURL), "/"); baseURL != "" {
+		opts = append(opts, telego.WithAPIServer(baseURL))
+	}
+
 	bot, err := telego.NewBot(telegramCfg.Token, opts...)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create telegram bot: %w", err)

pkg/config/config.go

@@ -237,6 +237,7 @@ type WhatsAppConfig struct {
 type TelegramConfig struct {
 	Enabled            bool                `json:"enabled"                 env:"PICOCLAW_CHANNELS_TELEGRAM_ENABLED"`
 	Token              string              `json:"token"                   env:"PICOCLAW_CHANNELS_TELEGRAM_TOKEN"`
+	BaseURL            string              `json:"base_url"                env:"PICOCLAW_CHANNELS_TELEGRAM_BASE_URL"`
 	Proxy              string              `json:"proxy"                   env:"PICOCLAW_CHANNELS_TELEGRAM_PROXY"`
 	AllowFrom          FlexibleStringSlice `json:"allow_from"              env:"PICOCLAW_CHANNELS_TELEGRAM_ALLOW_FROM"`
 	GroupTrigger       GroupTriggerConfig  `json:"group_trigger,omitempty"`