feat: expose verified JWT claims as peek_verified_claims conn assign

After verify_peek_auth succeeds, the full decoded claims map is now
assigned to conn.assigns[:peek_verified_claims]. This lets downstream
apps read any claim (e.g. locale) without re-verifying the token or
manually decoding the JWT payload.

Previously the claims were parsed and discarded after building
peek_account_user, forcing apps to either re-verify or base64-decode
the raw token to access additional fields.

Author: martinatpeek

lib/peek_app_sdk/plugs/peek_auth.ex

@@ -56,6 +56,7 @@ defmodule PeekAppSDK.Plugs.PeekAuth do
         |> assign(:peek_install_id, install_id)
         |> assign(:peek_account_user, build_account_user(claims))
         |> assign(:peek_config_id, config_id)
+        |> assign(:peek_verified_claims, claims)
 
       _ ->
         conn

test/peek_app_sdk/plugs/peek_auth_test.exs

@@ -27,6 +27,8 @@ defmodule PeekAppSDK.Plugs.PeekAuthTest do
       assert conn.assigns.peek_install_id == install_id
       assert conn.assigns.peek_install_token == token
       assert conn.assigns.peek_config_id == nil
+      assert is_map(conn.assigns.peek_verified_claims)
+      assert conn.assigns.peek_verified_claims["sub"] == install_id
 
       # Don't test session in tests since it's not properly initialized
       # and we're now handling that gracefully in the implementation