fix setup flow stale state and Stripe URL issues

Onboarding: re-fetch setup_status() after provider/Stripe connect instead
of manually patching the local assigns, which could miss admin_created and
leave users stuck on the setup page with no way forward.

Dev config: respect PHX_HOST for endpoint URL so Stripe checkout redirects
to the correct host instead of always using localhost.

Stripe setup: detect private/LAN IPs (10.x, 172.16-31.x, 192.168.x) as
unreachable, not just localhost — prevents creating webhook endpoints that
Stripe can never reach.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

config/dev.exs

@@ -21,6 +21,10 @@ config :berrypod, Berrypod.Repo,
 config :berrypod, BerrypodWeb.Endpoint,
   # Binding to loopback ipv4 address prevents access from other machines.
   # Change to `ip: {0, 0, 0, 0}` to allow access from other machines.
+  url: [
+    host: System.get_env("PHX_HOST") || "localhost",
+    port: String.to_integer(System.get_env("PORT") || "4000")
+  ],
   http: [ip: {0, 0, 0, 0}, port: String.to_integer(System.get_env("PORT") || "4000")],
   check_origin: false,
   code_reloader: true,