feat(feishu): add Lark (international) support via IsLark config field

Add IsLark field to FeishuConfig to switch between Feishu and Lark
domains. Also fix domain inconsistency where WS client defaulted to
LarkBaseUrl while HTTP client used FeishuBaseUrl.

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

pkg/channels/feishu/feishu_64.go

@@ -54,11 +54,15 @@ func NewFeishuChannel(cfg config.FeishuConfig, bus *bus.MessageBus) (*FeishuChan
 	)
 
 	tc := newTokenCache()
+	opts := []lark.ClientOptionFunc{lark.WithTokenCache(tc)}
+	if cfg.IsLark {
+		opts = append(opts, lark.WithOpenBaseUrl(lark.LarkBaseUrl))
+	}
 	ch := &FeishuChannel{
 		BaseChannel: base,
 		config:      cfg,
 		tokenCache:  tc,
-		client:      lark.NewClient(cfg.AppID, cfg.AppSecret, lark.WithTokenCache(tc)),
+		client:      lark.NewClient(cfg.AppID, cfg.AppSecret, opts...),
 	}
 	ch.SetOwner(ch)
 	return ch, nil
@@ -83,10 +87,15 @@ func (c *FeishuChannel) Start(ctx context.Context) error {
 
 	c.mu.Lock()
 	c.cancel = cancel
+	domain := lark.FeishuBaseUrl
+	if c.config.IsLark {
+		domain = lark.LarkBaseUrl
+	}
 	c.wsClient = larkws.NewClient(
 		c.config.AppID,
 		c.config.AppSecret,
 		larkws.WithEventHandler(dispatcher),
+		larkws.WithDomain(domain),
 	)
 	wsClient := c.wsClient
 	c.mu.Unlock()

pkg/config/config.go

@@ -325,6 +325,7 @@ type FeishuConfig struct {
 	Placeholder         PlaceholderConfig   `json:"placeholder,omitempty"`
 	ReasoningChannelID  string              `json:"reasoning_channel_id"    env:"PICOCLAW_CHANNELS_FEISHU_REASONING_CHANNEL_ID"`
 	RandomReactionEmoji FlexibleStringSlice `json:"random_reaction_emoji"   env:"PICOCLAW_CHANNELS_FEISHU_RANDOM_REACTION_EMOJI"`
+	IsLark              bool                `json:"is_lark"                 env:"PICOCLAW_CHANNELS_FEISHU_IS_LARK"`
 }
 
 type DiscordConfig struct {