feat(tool): markdown format in output web_fetch tool

pkg/config/config.go

@@ -694,6 +694,7 @@ type WebToolsConfig struct {
 	// For authenticated proxies, prefer HTTP_PROXY/HTTPS_PROXY env vars instead of embedding credentials in config.
 	Proxy           string `json:"proxy,omitempty"             env:"PICOCLAW_TOOLS_WEB_PROXY"`
 	FetchLimitBytes int64  `json:"fetch_limit_bytes,omitempty" env:"PICOCLAW_TOOLS_WEB_FETCH_LIMIT_BYTES"`
+	Format          string `json:"format,omitempty"            env:"PICOCLAW_TOOLS_WEB_FORMAT"`
 }
 
 type CronToolsConfig struct {

pkg/config/defaults.go

@@ -412,6 +412,7 @@ func DefaultConfig() *Config {
 				},
 				Proxy:           "",
 				FetchLimitBytes: 10 * 1024 * 1024, // 10MB by default
+				Format:          "plaintext",
 				Brave: BraveConfig{
 					Enabled:    false,
 					APIKey:     "",