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.

test/mv_web/controllers/oidc_passwordless_linking_test.exs

@@ -45,7 +45,7 @@ defmodule MvWeb.OidcPasswordlessLinkingTest do
       # Now OIDC sign-in should work
       result =
         Mv.Accounts.User
-        |> Ash.Query.for_read(:sign_in_with_rauthy, %{
+        |> Ash.Query.for_read(:sign_in_with_oidc, %{
           user_info: %{
             "sub" => "auto_link_oidc_123",
             "preferred_username" => "invited@example.com"
@@ -79,7 +79,7 @@ defmodule MvWeb.OidcPasswordlessLinkingTest do
       }
 
       result =
-        Mv.Accounts.create_register_with_rauthy(%{
+        Mv.Accounts.create_register_with_oidc(%{
           user_info: user_info,
           oauth_tokens: %{"access_token" => "test_token"}
         })
@@ -119,7 +119,7 @@ defmodule MvWeb.OidcPasswordlessLinkingTest do
       }
 
       result =
-        Mv.Accounts.create_register_with_rauthy(%{
+        Mv.Accounts.create_register_with_oidc(%{
           user_info: user_info,
           oauth_tokens: %{"access_token" => "test_token"}
         })
@@ -165,7 +165,7 @@ defmodule MvWeb.OidcPasswordlessLinkingTest do
       }
 
       result =
-        Mv.Accounts.create_register_with_rauthy(%{
+        Mv.Accounts.create_register_with_oidc(%{
           user_info: user_info,
           oauth_tokens: %{"access_token" => "test_token"}
         })
@@ -200,7 +200,7 @@ defmodule MvWeb.OidcPasswordlessLinkingTest do
       }
 
       result =
-        Mv.Accounts.create_register_with_rauthy(%{
+        Mv.Accounts.create_register_with_oidc(%{
           user_info: user_info,
           oauth_tokens: %{"access_token" => "test_token"}
         })