Fix blank episode form: move all CSS to external static files

- Go html/template rejects <style> blocks and inline style attributes
  when template expressions are present in URL/CSS contexts
- Move all inline CSS to static/auth.css, static/episode.css,
  static/dashboard.css
- Serve static files from embedded FS via /static/ handler
- Fix missing </div> in episode form audio file group

main.go

@@ -15,6 +15,9 @@ import (
 //go:embed template/*.html
 var templateFS embed.FS
 
+//go:embed static/*
+var staticFS embed.FS
+
 func main() {
 	dbPath := os.Getenv("PODSTALK_DB")
 	if dbPath == "" {
@@ -81,6 +84,8 @@ func main() {
 
 	// Public uploaded files.
 	http.HandleFunc("/uploads/", epH.ServeUpload)
+	// Static files.
+	http.Handle("/static/", http.FileServer(http.FS(staticFS)))
 
 	port := envOrDefault("PORT", "8080")
 	addr := fmt.Sprintf(":%s", port)