test: fix all compile warnings in test/

Three categories of warnings fixed:

1. Unused variable: rename authorize_url to _authorize_url in the
   callback-receive block (the value is only used to consume the
   message from the test mailbox).

2. Deprecated map.field() with parentheses: save_token_for_test/2
   used token.access_token() etc. to read a map field, which the
   compiler now warns about (must drop the parens).

3. @deprecated function calls: enable_alert/2, disable_alert/2, and
   trading_days/4 are all marked @deprecated in lib/, so the tests
   that exercised them emitted a deprecation warning at compile
   time. Deleted those three describe blocks.

Test deletions (AGENTS.md notes this requires justification in the
commit body): the deleted tests exist only to exercise functions the
library has explicitly marked @deprecated. They provide no coverage
of the new APIs (which have their own tests elsewhere) and will need
to be removed anyway when the deprecated functions are dropped
upstream. Keeping them solely to dodge a compile warning would also
require either deleting the test (lossy) or wrapping calls in
apply/3 (ugly, hides intent). Per user request, deletion was the
chosen path.

Author: gilbertwong96

test/longbridge/alert_context_test.exs

@@ -230,44 +230,6 @@ defmodule Longbridge.AlertContextTest do
     end
   end
 
-  describe "enable_alert/2 (deprecated)" do
-    test "POSTs enable: true with the alert_id" do
-      server =
-        start_fake_http_server(fn request, socket ->
-          {method, path, body} = parse_request(request)
-          assert method == "POST"
-          assert path == "/v1/notify/reminders"
-          decoded = JSON.decode!(body)
-          assert decoded["alert_id"] == "alert-1"
-          assert decoded["enable"] == true
-
-          :gen_tcp.send(socket, http_ok(JSON.encode!(%{"code" => 0, "data" => %{}})))
-        end)
-
-      assert {:ok, _} = AlertContext.enable_alert(config_with(server.port), "alert-1")
-      stop_fake_http_server(server)
-    end
-  end
-
-  describe "disable_alert/2 (deprecated)" do
-    test "POSTs enable: false with the alert_id" do
-      server =
-        start_fake_http_server(fn request, socket ->
-          {method, path, body} = parse_request(request)
-          assert method == "POST"
-          assert path == "/v1/notify/reminders"
-          decoded = JSON.decode!(body)
-          assert decoded["alert_id"] == "alert-2"
-          assert decoded["enable"] == false
-
-          :gen_tcp.send(socket, http_ok(JSON.encode!(%{"code" => 0, "data" => %{}})))
-        end)
-
-      assert {:ok, _} = AlertContext.disable_alert(config_with(server.port), "alert-2")
-      stop_fake_http_server(server)
-    end
-  end
-
   describe "http_url per-call override" do
     test "list_alerts/2 hits the URL passed in opts" do
       server =

test/longbridge/market_context_test.exs

@@ -246,13 +246,6 @@ defmodule Longbridge.MarketContextTest do
     end
   end
 
-  describe "trading_days/4" do
-    test "returns :removed_upstream" do
-      assert {:error, :removed_upstream} =
-               MarketContext.trading_days(config_with(0), "2024-01-01", "2024-12-31", "US")
-    end
-  end
-
   describe "top_movers/2" do
     test "POSTs with encoded sort atom" do
       server =

test/longbridge/oauth_test.exs

@@ -425,10 +425,10 @@ defmodule Longbridge.OAuthTest do
 
     json =
       JSON.encode!(%{
-        access_token: token.access_token(),
-        refresh_token: token.refresh_token(),
-        expires_at: token.expires_at(),
-        token_type: token.token_type(),
+        access_token: token.access_token,
+        refresh_token: token.refresh_token,
+        expires_at: token.expires_at,
+        token_type: token.token_type,
         http_url: token[:http_url]
       })
 
@@ -852,7 +852,7 @@ defmodule Longbridge.OAuthTest do
           )
         end)
 
-      authorize_url =
+      _authorize_url =
         receive do
           {:authorize_url, url} -> url
         after