SAFETY-04 review fixes: the freeze deadlocked, the bound was too loose

S-1. The frozen branch admitted a correction only if it shrank |i_w|. That is
unsatisfiable for BOTH signs of error whenever |correction| > 2*|i_w|, i.e.
whenever the integrator is near zero, so the loop stopped moving and the freeze
could never clear - it clears when the inverter tracks, and not tracking is
what saturation means. Measured: 0 W held into a 2 kW import indefinitely,
where release/1.0 recovers on the next cycle. Re-encoded as the same asymmetric
rule the output freeze has always used: may not wind further in the direction
it is already pushing, may fall, cross zero or reverse. Same interpretation,
an encoding that cannot deadlock.

S-2. integrator_max_w defaulted to 1.5x max_w, which ADDED windup: in
release/1.0 the accumulator was the post-clamp command and could never pass the
rail. Default is now "follow max_w" (config 0 = unset). Measured on the 4000 W
load-drop sim, first cycle after the drop: 1000 W at the new default, 1800 W at
3000. DOCS row inverted - the useful direction is below max_w, and the 14 768 W
anecdote is a vendor controller, not evidence about this code.

S-3. The claim that i_w=None preserved release/1.0 exactly was false, because
the S-1 gate ran regardless of seeding. It is true again, and now asserted
rather than asserted-about: 3024-case exhaustive comparison against a
transcription of the old law, over both freeze states, both signs and either
side of the deadband. Added the carried-i_w convergence/overshoot sim that the
shipped configuration was missing.

S-4. Cycles are distinct meter values, not seconds: cycle() runs only when the
meter reading changes, so the window has no wall-clock bound. Comment and DOCS
corrected; the stall is detection latency, not a windup hazard, because the
same condition stalls the whole loop.

test_control.py: 33 -> 41 checks, all passing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Du77usMj8XNKNFZGmUiWDa

goodwe_controller/app/main.py

@@ -70,7 +70,11 @@ class Controller:
             step_w=int(opts.get("step_w", 10)),
             saturation_w=float(opts.get("saturation_w", 500)),
             saturation_cycles=int(opts.get("saturation_cycles", 3)),
-            integrator_max_w=float(opts.get("integrator_max_w", 3000)),
+            # 0 / unset means "follow max_w", which is the recommended
+            # value. Read the note in control.py before raising it above
+            # max_w: every watt above the rail is unwind latency.
+            integrator_max_w=(float(opts["integrator_max_w"])
+                              if opts.get("integrator_max_w") else None),
         )
         self.maint = Maintenance(
             MaintConfig(