feat(chat): add auto-summarization with token tracking UI

Add /summarize command, token usage bar, and summary endpoint.
Add JSON tags to config/platform/scanner structs for API serialization.

💘 Generated with Crush

Assisted-by: MiniMax-M2.7 via Crush <crush@charm.land>

internal/platform/platform.go

@@ -24,12 +24,12 @@ const (
 )
 
 type SystemInfo struct {
-	OS            OS
-	Arch          Arch
-	IsWSL         bool
-	Shell         string
-	Terminal      string
-	PackageManager string
+	OS             OS     `json:"os"`
+	Arch           Arch   `json:"arch"`
+	IsWSL          bool   `json:"is_wsl"`
+	Shell          string `json:"shell"`
+	Terminal       string `json:"terminal"`
+	PackageManager string `json:"package_manager"`
 }
 
 func Detect() SystemInfo {