Slug-based RSS URLs and success flash messages

- Add podcast_slug to users with global uniqueness check
- RSS available at /rss/{slug} (path-based) with legacy ?slug= fallback
- Slug field in dashboard settings with validation (lowercase, hyphens)
- JS flash messages for success/error after form submissions
- Remove unused imports

handler/settings.go

@@ -4,10 +4,13 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"regexp"
 
 	"podstalk/store"
 )
 
+var slugRe = regexp.MustCompile(`^[a-z0-9]+(-[a-z0-9]+)*$`)
+
 type SettingsHandler struct {
 	Store     *store.Store
 	UploadDir string
@@ -36,6 +39,26 @@ func (h *SettingsHandler) ServeSettings(w http.ResponseWriter, r *http.Request)
 		title = user.PodcastTitle
 	}
 
+	slug := r.FormValue("podcast_slug")
+	if slug == "" {
+		slug = user.PodcastSlug
+	}
+	if slug != "" {
+		if !slugRe.MatchString(slug) {
+			http.Redirect(w, r, "/?error=slug+must+be+lowercase+letters+numbers+and+hyphens", http.StatusSeeOther)
+			return
+		}
+		taken, err := h.Store.SlugTaken(slug, userID)
+		if err != nil {
+			http.Redirect(w, r, "/?error=internal+error", http.StatusSeeOther)
+			return
+		}
+		if taken {
+			http.Redirect(w, r, "/?error=slug+already+taken", http.StatusSeeOther)
+			return
+		}
+	}
+
 	author := r.FormValue("podcast_author")
 	if author == "" {
 		author = user.PodcastAuthor
@@ -48,7 +71,6 @@ func (h *SettingsHandler) ServeSettings(w http.ResponseWriter, r *http.Request)
 	if err == nil {
 		defer file.Close()
 
-		// Remove old image
 		if image != "" {
 			os.Remove(filepath.Join(h.UploadDir, image))
 		}
@@ -68,6 +90,6 @@ func (h *SettingsHandler) ServeSettings(w http.ResponseWriter, r *http.Request)
 		}
 	}
 
-	h.Store.UpdateUserPodcast(userID, title, image, author)
-	http.Redirect(w, r, "/", http.StatusSeeOther)
+	h.Store.UpdateUserPodcast(userID, title, slug, image, author)
+	http.Redirect(w, r, "/?success=podcast+settings+saved", http.StatusSeeOther)
 }