Rename task_* tables to quest_* with legacy-dev migration path (D-007)

Per design/IMPLEMENTATION-ORDER.md 1.1 and decision D-007: the domain
model takes the quest vocabulary pre-release. SCHEMA_V1 now creates
quest_definitions/quest_instances directly; DAO classes, records and
error messages follow (QuestDefinitionsDao, QuestInstancesDao). The
migration runner gains migration 2, an async-callable step that detects
surviving task_* tables on dev machines and ALTER TABLE RENAMES them
inside the migration transaction, with FK clauses rewritten by SQLite.
Migration 1's content rewrite is legal because nothing was ever
shipped; dev databases stamped version 1 ride migration 2 up to 2.

tests/test_lifecycle.py

@@ -247,12 +247,12 @@ async def test_setup_applies_all_v1_tables(hass, make_entry) -> None:
     rows = await database.fetch_all(
         "SELECT name FROM sqlite_master WHERE type = 'table' "
         "AND name IN ('children', 'admin_users', 'schedule_rules', "
-        "'task_definitions') ORDER BY name"
+        "'quest_definitions') ORDER BY name"
     )
     assert [row[0] for row in rows] == [
         "admin_users",
         "children",
+        "quest_definitions",
         "schedule_rules",
-        "task_definitions",
     ]
     await async_unload_entry(hass, entry)