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_clamp.py

@@ -1969,9 +1969,11 @@ print("9. SAFETY-40: the integrator bound is not a BUG SIGNAL, and the numbers "
 # The fixtures are chosen so the numbers the old text used DIFFER from the true
 # ones (MUTATION.md habit 4); the PRECONDITION checks pin that.
 import logging
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), "tools"))  # noqa: E402
+import main_files  # noqa: E402
 import app.main as _main_mod
 
-_real_compute = _main_mod.compute
+_real_compute = main_files.live.compute
 
 
 class _LogCap(logging.Handler):
@@ -1995,7 +1997,7 @@ def s40_run(grid, cycles, track, **over):
     cap = _LogCap()
     lg = logging.getLogger("goodwe")
     lg.addHandler(cap)
-    _main_mod.compute = spy
+    main_files.live.compute = spy
 
     async def go():
         hass = _Hass(grid, track=track)
@@ -2024,7 +2026,7 @@ def s40_run(grid, cycles, track, **over):
     try:
         hass, c, red = asyncio.run(go())
     finally:
-        _main_mod.compute = _real_compute
+        main_files.live.compute = _real_compute
         lg.removeHandler(cap)
     return ticks, hass, c, red, cap.records
 
@@ -2104,8 +2106,7 @@ check("...and its ERROR says it is a software fault and that control keeps "
       any(x.levelno == logging.ERROR and "software fault" in x.getMessage()
           and "control runs on" in x.getMessage() for x in log_o)
       and "reached 14 768 W on this project" in
-      open(os.path.join(os.path.dirname(os.path.abspath(__file__)), "app",
-                        "main.py"), encoding="utf-8").read())
+      main_files.source())
 check("...under the over-rating title, quoting a tick's own asked and sent "
       "numbers in that order, with a red status row",
       clamp_notes(hass_o)