feat(embedded): add Perses + VictoriaMetrics subprocess management with auto-download

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/claude-agent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/embedded/dashboard.go

@@ -0,0 +1,12 @@
+package embedded
+
+import (
+	"embed"
+)
+
+//go:embed dashboard/proxy.json
+var dashboardFS embed.FS
+
+func DashboardJSON() ([]byte, error) {
+	return dashboardFS.ReadFile("dashboard/proxy.json")
+}