feat(channel-monitor): add feature switch settings + fix extra_models save

Settings:
- New "功能开关" tab between 通用设置 and 安全与认证
- ChannelMonitorEnabled toggle: runner skips scheduling when false,
  user-facing list returns empty
- ChannelMonitorDefaultIntervalSeconds (15-3600): pre-fills interval
  when creating a new monitor; each monitor can still override

Bug fix:
- ModelTagInput now commits pending input on blur, not just Enter/Tab.
  Previously clicking "save" with an un-Enter'd extra model would drop
  the value (DB stored extra_models=[] even when user typed entries).

Backend:
- domain_constants: SettingKeyChannelMonitor{Enabled,DefaultIntervalSeconds}
- SettingService.GetChannelMonitorRuntime: lightweight getter used by
  runner tick + user handler per-request (fail-open on DB error)
- Runner tickDueChecks: bails early when feature disabled
- ChannelMonitorUserHandler: checks feature flag before serving
- Comment on runner doc: scheduler state is implicit (every tick re-reads
  ListEnabled from DB), so CRUD ops on monitors self-maintain the schedule

Bump VERSION to 0.1.114.25

backend/internal/service/setting_service.go

@@ -450,6 +450,8 @@ func (s *SettingService) GetPublicSettings(ctx context.Context) (*PublicSettings
 		SettingKeyBalanceLowNotifyThreshold,
 		SettingKeyBalanceLowNotifyRechargeURL,
 		SettingKeyAccountQuotaNotifyEnabled,
+		SettingKeyChannelMonitorEnabled,
+		SettingKeyChannelMonitorDefaultIntervalSeconds,
 	}
 
 	settings, err := s.settingRepo.GetMultiple(ctx, keys)
@@ -532,9 +534,67 @@ func (s *SettingService) GetPublicSettings(ctx context.Context) (*PublicSettings
 		AccountQuotaNotifyEnabled:        settings[SettingKeyAccountQuotaNotifyEnabled] == "true",
 		BalanceLowNotifyThreshold:        balanceLowNotifyThreshold,
 		BalanceLowNotifyRechargeURL:      settings[SettingKeyBalanceLowNotifyRechargeURL],
+
+		ChannelMonitorEnabled:                !isFalseSettingValue(settings[SettingKeyChannelMonitorEnabled]),
+		ChannelMonitorDefaultIntervalSeconds: parseChannelMonitorInterval(settings[SettingKeyChannelMonitorDefaultIntervalSeconds]),
 	}, nil
 }
 
+// channelMonitorIntervalMin / channelMonitorIntervalMax bound the default interval
+// (mirrors the monitor-level constraint but lives here so setting_service stays decoupled).
+const (
+	channelMonitorIntervalMin     = 15
+	channelMonitorIntervalMax     = 3600
+	channelMonitorIntervalFallback = 60
+)
+
+// parseChannelMonitorInterval parses the stored string and clamps to [15, 3600].
+// Empty / invalid input falls back to channelMonitorIntervalFallback.
+func parseChannelMonitorInterval(raw string) int {
+	v, err := strconv.Atoi(strings.TrimSpace(raw))
+	if err != nil {
+		return channelMonitorIntervalFallback
+	}
+	return clampChannelMonitorInterval(v)
+}
+
+// clampChannelMonitorInterval clamps v to the allowed range. 0 means "not provided".
+func clampChannelMonitorInterval(v int) int {
+	if v <= 0 {
+		return 0
+	}
+	if v < channelMonitorIntervalMin {
+		return channelMonitorIntervalMin
+	}
+	if v > channelMonitorIntervalMax {
+		return channelMonitorIntervalMax
+	}
+	return v
+}
+
+// ChannelMonitorRuntime is the lightweight view of the channel monitor feature
+// consumed by the runner and user-facing handlers.
+type ChannelMonitorRuntime struct {
+	Enabled                 bool
+	DefaultIntervalSeconds  int
+}
+
+// GetChannelMonitorRuntime reads the channel monitor feature flags directly from
+// the settings store. Fail-open: on error returns Enabled=true with the default interval.
+func (s *SettingService) GetChannelMonitorRuntime(ctx context.Context) ChannelMonitorRuntime {
+	vals, err := s.settingRepo.GetMultiple(ctx, []string{
+		SettingKeyChannelMonitorEnabled,
+		SettingKeyChannelMonitorDefaultIntervalSeconds,
+	})
+	if err != nil {
+		return ChannelMonitorRuntime{Enabled: true, DefaultIntervalSeconds: channelMonitorIntervalFallback}
+	}
+	return ChannelMonitorRuntime{
+		Enabled:                !isFalseSettingValue(vals[SettingKeyChannelMonitorEnabled]),
+		DefaultIntervalSeconds: parseChannelMonitorInterval(vals[SettingKeyChannelMonitorDefaultIntervalSeconds]),
+	}
+}
+
 // SetOnUpdateCallback sets a callback function to be called when settings are updated
 // This is used for cache invalidation (e.g., HTML cache in frontend server)
 func (s *SettingService) SetOnUpdateCallback(callback func()) {
@@ -1085,6 +1145,12 @@ func (s *SettingService) buildSystemSettingsUpdates(ctx context.Context, setting
 		updates[SettingKeyOpsMetricsIntervalSeconds] = strconv.Itoa(settings.OpsMetricsIntervalSeconds)
 	}
 
+	// Channel monitor feature switch
+	updates[SettingKeyChannelMonitorEnabled] = strconv.FormatBool(settings.ChannelMonitorEnabled)
+	if v := clampChannelMonitorInterval(settings.ChannelMonitorDefaultIntervalSeconds); v > 0 {
+		updates[SettingKeyChannelMonitorDefaultIntervalSeconds] = strconv.Itoa(v)
+	}
+
 	// Claude Code version check
 	updates[SettingKeyMinClaudeCodeVersion] = settings.MinClaudeCodeVersion
 	updates[SettingKeyMaxClaudeCodeVersion] = settings.MaxClaudeCodeVersion
@@ -1630,6 +1696,10 @@ func (s *SettingService) InitializeDefaultSettings(ctx context.Context) error {
 		SettingKeyOpsQueryModeDefault:          "auto",
 		SettingKeyOpsMetricsIntervalSeconds:    "60",
 
+		// Channel monitor defaults (enabled, 60s)
+		SettingKeyChannelMonitorEnabled:                "true",
+		SettingKeyChannelMonitorDefaultIntervalSeconds: "60",
+
 		// Claude Code version check (default: empty = disabled)
 		SettingKeyMinClaudeCodeVersion: "",
 		SettingKeyMaxClaudeCodeVersion: "",
@@ -1932,6 +2002,12 @@ func (s *SettingService) parseSettings(settings map[string]string) *SystemSettin
 		}
 	}
 
+	// Channel monitor feature (default: enabled, 60s)
+	result.ChannelMonitorEnabled = !isFalseSettingValue(settings[SettingKeyChannelMonitorEnabled])
+	result.ChannelMonitorDefaultIntervalSeconds = parseChannelMonitorInterval(
+		settings[SettingKeyChannelMonitorDefaultIntervalSeconds],
+	)
+
 	// Claude Code version check
 	result.MinClaudeCodeVersion = settings[SettingKeyMinClaudeCodeVersion]
 	result.MaxClaudeCodeVersion = settings[SettingKeyMaxClaudeCodeVersion]