refactor(navidrome): replace custom Caddy build with pre-built image

Remove custom Dockerfile.caddy and use caddybuilds/caddy-namecheap:2-alpine
image directly in docker-compose.yml to simplify deployment

navidrome/Dockerfile.caddy

@@ -1,7 +0,0 @@
-from caddy:2.9-builder-alpine as builder
-
-run xcaddy build \
-    --with github.com/caddy-dns/namecheap
-
-from caddy:alpine
-copy --from=builder /usr/bin/caddy /usr/bin/caddy

navidrome/docker-compose.yml

@@ -22,9 +22,7 @@ services:
       - internal
 
   reverse_proxy:
-    build:
-      context: .
-      dockerfile: Dockerfile.caddy
+    image: caddybuilds/caddy-namecheap:2-alpine
     restart: unless-stopped
     network_mode: service:tailscale
     volumes: