feat(agent): adaptive tool timing with slow tool notification

Track per-tool execution time statistics in session metadata. When a tool
call exceeds its adaptive threshold (2x historical max, min 120s default),
send a direct outbound notification to the user.

- ToolTimingMap: parse/serialize/record/threshold from session metadata
- StartSlowTimer: fires once per tool call, auto-cancels on completion
- Team config: slow_tool toggle (default on, always direct, never leader)
- UI: toggle in team settings with i18n (en/vi/zh)
- Store: add GetSessionMetadata to session store interface

internal/tools/team_notify_config.go

@@ -8,6 +8,7 @@ type TeamNotifyConfig struct {
 	Progress   bool   `json:"progress"`   // member updates progress
 	Failed     bool   `json:"failed"`     // task failed
 	Completed  bool   `json:"completed"`  // task completed
+	SlowTool   bool   `json:"slow_tool"`  // system alert when tool call exceeds adaptive threshold (always direct, never through leader)
 	Mode       string `json:"mode"`       // "direct" (outbound) or "leader" (through leader agent)
 }
 
@@ -18,6 +19,7 @@ func DefaultTeamNotifyConfig() TeamNotifyConfig {
 		Progress:   true,
 		Failed:     true,
 		Completed:  true,
+		SlowTool:   true,
 		Mode:       "direct",
 	}
 }
@@ -35,6 +37,7 @@ func ParseTeamNotifyConfig(settings json.RawMessage) TeamNotifyConfig {
 			Progress   *bool  `json:"progress"`
 			Failed     *bool  `json:"failed"`
 			Completed  *bool  `json:"completed"`
+			SlowTool   *bool  `json:"slow_tool"`
 			Mode       string `json:"mode"`
 		} `json:"notifications"`
 	}
@@ -54,6 +57,9 @@ func ParseTeamNotifyConfig(settings json.RawMessage) TeamNotifyConfig {
 	if n.Completed != nil {
 		cfg.Completed = *n.Completed
 	}
+	if n.SlowTool != nil {
+		cfg.SlowTool = *n.SlowTool
+	}
 	if n.Mode == "leader" {
 		cfg.Mode = "leader"
 	}