[lvgl] Use contextvars to improve lvgl scheduling (#19242)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

tests/unit_tests/components/lvgl/test_table_codegen.py

@@ -5,7 +5,6 @@ from __future__ import annotations
 import pytest
 
 from esphome.automation import ACTION_REGISTRY
-from esphome.components.lvgl.defines import set_widgets_completed
 from esphome.components.lvgl.lvcode import LvContext
 from esphome.components.lvgl.schemas import container_schema
 from esphome.components.lvgl.trigger import generate_triggers
@@ -151,7 +150,6 @@ async def test_selected_cell_omitted_entirely_when_not_configured(
 @pytest.mark.asyncio
 async def test_cell_update_action_writes_only_the_given_fields(setup_core) -> None:
     await _create_table({"id": "table_update", "rows": [["a", "b"], ["c", "d"]]})
-    set_widgets_completed(True)
     # Only inspect statements emitted by the action below, not by creation.
     before = len(_statements())
 
@@ -194,7 +192,6 @@ async def test_on_value_registers_a_value_changed_event_callback(setup_core) ->
     parent = MockObj("parent_obj")
     async with LvContext():
         await widget_to_code(config, table_spec, parent)
-        set_widgets_completed(True)
         await generate_triggers()
 
     statements = _statements()