MAINT-21: tests read and patch the Controller through tools/main_files.py

Prepares the split of app/main.py's Controller into files by job, with no app
change. tools/main_files.py gives a test the text and the AST of main.py plus
the files split from it, and `live`, which sets a global in every file whose
functions read it (and raises when none does). Tests that read main.py's
source, and tests and replay tools that patch a main global (datetime,
compute, resolve, _mono, WRITE_BUDGET_S, ...), go through it, so they pass on
this layout and on the split one. test_split_patches.py fails when a test or
tool patches an app.main attribute that main.py no longer reads, or that
another file also reads. tools/maint21_same_ast.py proves every function,
method and module-level assignment of main.py at the base is found unchanged
in its new file.

Co-Authored-By: Claude <noreply@anthropic.com>

goodwe_controller/test_maint10.py

@@ -22,6 +22,7 @@ from pathlib import Path
 
 sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), "tools"))
 
+import main_files  # noqa: E402
 import app.main as M                                        # noqa: E402
 from app import maintenance as MT                           # noqa: E402
 from app.maintenance import (                               # noqa: E402
@@ -367,7 +368,7 @@ def amain_zone(zone_body, env_tz):
 
     M.load_options = lambda: {"setpoint_entity": "number.sp"}
     M.HomeAssistant = lambda session, **kw: _Hass()
-    M.validate_startup_config = lambda *a, **k: []
+    main_files.live.validate_startup_config = lambda *a, **k: []
     M.mode_announcement = lambda opts, store: ((), ())
     M.Controller = _controller
     M.aiohttp.ClientSession = lambda *a, **k: _Session(zone_body)