Per-user podcasts, file uploads, RSS images, Docker support

- Each user owns a podcast: podcast title/author/image on users table
- Episodes scoped by user_id with context-based auth
- Audio file upload replaces URL linking, served from /uploads/
- Podcast and per-episode images with itunes:image in RSS
- RSS per-user via ?user=N, dashboard shows user-specific feed URL
- Settings form for title + author + image per user
- Docker multi-stage build (golang:1.25-alpine / alpine:3.21)
- Removed PODSTALK_TITLE/AUTHOR env vars

main.go

@@ -59,13 +59,11 @@ func main() {
 		UploadDir: uploadDir,
 	}
 	rssH := &handler.RSSHandler{
-		Store:     st,
-		BaseTitle: envOrDefault("PODSTALK_TITLE", "Podstalk"),
-		Link:      baseURL,
-		Author:    envOrDefault("PODSTALK_AUTHOR", "Podstalk"),
+		Store: st,
+		Link:  baseURL,
 	}
 
-	// Auth routes — redirect to dashboard if already signed in.
+	// Auth routes.
 	http.HandleFunc("/signup", authMid.RedirectIfAuthed(authH.ServeSignup))
 	http.HandleFunc("/signin", authMid.RedirectIfAuthed(authH.ServeSignin))
 	http.HandleFunc("/signout", authH.ServeSignout)
@@ -77,7 +75,7 @@ func main() {
 	http.HandleFunc("/episodes/delete", authMid.RequireAuth(epH.ServeDelete))
 	http.HandleFunc("/settings", authMid.RequireAuth(setH.ServeSettings))
 
-	// Public RSS feed.
+	// Public RSS feed — per-user via ?user=N query param.
 	http.HandleFunc("/rss", rssH.ServeRSS)
 
 	// Public uploaded files.