Rename OIDC strategy from :rauthy to :oidc, update callback path

- Rename AshAuthentication strategy from :oidc :rauthy to :oidc :oidc;
  generated actions are now register_with_oidc / sign_in_with_oidc.
- Update config keys (:rauthy → :oidc) in dev.exs and runtime.exs.
- Update default_redirect_uri to /auth/user/oidc/callback everywhere.
- Rename Mv.Accounts helper functions accordingly.
- Update Mv.Secrets, AuthController, link_oidc_account_live and all tests.
- Update docker-compose.prod.yml, .env.example, README and docs.

IMPORTANT: OIDC providers must be updated to use the new redirect URI
/auth/user/oidc/callback instead of /auth/user/rauthy/callback.

lib/accounts/accounts.ex

@@ -9,7 +9,7 @@ defmodule Mv.Accounts do
   ## Public API
   The domain exposes these main actions:
   - User CRUD: `create_user/1`, `list_users/0`, `update_user/2`, `destroy_user/1`
-  - Authentication: `create_register_with_rauthy/1`, `read_sign_in_with_rauthy/1`
+  - Authentication: `create_register_with_oidc/1`, `read_sign_in_with_oidc/1`
   """
   use Ash.Domain,
     extensions: [AshAdmin.Domain, AshPhoenix]
@@ -24,8 +24,8 @@ defmodule Mv.Accounts do
       define :list_users, action: :read
       define :update_user, action: :update_user
       define :destroy_user, action: :destroy
-      define :create_register_with_rauthy, action: :register_with_rauthy
-      define :read_sign_in_with_rauthy, action: :sign_in_with_rauthy
+      define :create_register_with_oidc, action: :register_with_oidc
+      define :read_sign_in_with_oidc, action: :sign_in_with_oidc
     end
 
     resource Mv.Accounts.Token