[fix]. Reply on unsupported @codex commands

tests/test_commands.py

@@ -1,4 +1,4 @@
-from gitea_codex_bot.services.commands import parse_command
+from gitea_codex_bot.services.commands import detect_prefixed_command, parse_command
 
 
 def test_parse_review_command_modes() -> None:
@@ -49,3 +49,11 @@ def test_parse_help_long_flag_and_arguments() -> None:
     assert cmd is not None
     assert cmd.name == "help"
     assert cmd.arguments == ["status", "quick"]
+
+
+def test_detect_prefixed_command_for_unsupported_name() -> None:
+    assert detect_prefixed_command("@codex shipit now", aliases={"codex"}) == "shipit"
+
+
+def test_detect_prefixed_command_returns_none_for_non_alias() -> None:
+    assert detect_prefixed_command("@someone review", aliases={"codex"}) is None