feat(config): add timezone setting to agents.defaults

Add a timezone field to AgentDefaults that overrides the process-wide
default timezone via time.Local at startup. This ensures all time.Now()
calls across cron, heartbeat, and agent context use the configured
timezone instead of relying on the server system timezone.

Also supports override via PICOCLAW_AGENTS_DEFAULTS_TIMEZONE env var.

config/config.example.json

@@ -2,6 +2,7 @@
   "agents": {
     "defaults": {
       "workspace": "~/.picoclaw/workspace",
+      "timezone": "Asia/Makassar",
       "restrict_to_workspace": true,
       "model": "gpt4",
       "max_tokens": 8192,
@@ -246,4 +247,4 @@
     "host": "0.0.0.0",
     "port": 18790
   }
-}
+}

pkg/config/config.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"sync/atomic"
+	"time"
 
 	"github.com/caarlos0/env/v11"
 )
@@ -167,6 +168,7 @@ type SessionConfig struct {
 }
 
 type AgentDefaults struct {
+	Timezone            string   `json:"timezone,omitempty"              env:"PICOCLAW_AGENTS_DEFAULTS_TIMEZONE"`
 	Workspace           string   `json:"workspace"                       env:"PICOCLAW_AGENTS_DEFAULTS_WORKSPACE"`
 	RestrictToWorkspace bool     `json:"restrict_to_workspace"           env:"PICOCLAW_AGENTS_DEFAULTS_RESTRICT_TO_WORKSPACE"`
 	Provider            string   `json:"provider"                        env:"PICOCLAW_AGENTS_DEFAULTS_PROVIDER"`
@@ -515,6 +517,15 @@ func LoadConfig(path string) (*Config, error) {
 		return nil, err
 	}
 
+	// Apply timezone from config — overrides process-wide default
+	if tz := cfg.Agents.Defaults.Timezone; tz != "" {
+		loc, err := time.LoadLocation(tz)
+		if err != nil {
+			return nil, fmt.Errorf("invalid timezone %q: %w", tz, err)
+		}
+		time.Local = loc
+	}
+
 	return cfg, nil
 }