feat: add /support command and improve fallback message

- Add `/support` command handler to initiate support flow via direct command
  (previously only accessible via callback button)
- Update `UNDEFINED_MESSAGE` to guide users toward `/support` and `/start`
  when they use undefined commands

handlers/support.py

@@ -25,6 +25,15 @@ async def support_init(cb: CallbackQuery, state: FSMContext):
     await state.set_state(SupportStorage.prompt)
 
 
+@router.message(Command("support"))
+async def support_init_cmd(msg: Message, state: FSMContext):
+    await state.clear()
+    await msg.delete()
+
+    await msg.answer(text=SUPPORT_INIT, reply_markup=return_to_menu)
+    await state.set_state(SupportStorage.prompt)
+
+
 @router.message(SupportStorage.prompt)
 async def received_message(
     msg: Message, state: FSMContext, session: AsyncSession, deps: DependenciesDTO