MAINT-15: the balancing hold ends on time with no SoC reading

HOLD's time check moves into Maintenance._hold(), used by step() and
_no_soc(). A hold that loses its SoC now ends at hold_min, writes
last_completed and logs the same COMPLETE line. The 15 min HOLD line says
the hold still ends at its normal time. Behaviour with a reading is
unchanged (differential trace against db9e231).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

goodwe_controller/test_maint14.py

@@ -245,8 +245,8 @@ m = in_charge()
 m.tick(T0 + MIN, 100.0)
 _, _, _, ev = run(m, T0 + 2 * MIN, 30, None)
 note = [e for e in ev if "no battery level for" in e]
-check("HOLD: the line exists and claims no time limit",
-      len(note) == 1 and "time limit" not in note[0] and "waits" in note[0])
+check("HOLD: the line exists and says the hold ends at its normal time (MAINT-15)",
+      len(note) == 1 and "normal time" in note[0] and "waits" not in note[0])
 m = in_charge()
 _, _, _, ev = run(m, T0, 30, None)
 check("charge keeps its wording", any("time limit of the charge" in e for e in ev))
@@ -268,7 +268,7 @@ _, _, out, _ = run(m, T0 + 10 * MIN, CHARGE_TIMEOUT_MIN + 20, None)
 _, _, _, ev = run(m, out[1] + MIN, 30, None)
 check("charge done with no SoC, then HOLD with no SoC: a new episode, so the "
       "HOLD line is said", out[0].phase == HOLD
-      and sum("hold waits" in e for e in ev) == 1)
+      and sum("normal time" in e for e in ev) == 1)
 
 print("6. restart while the SoC is missing")
 with tempfile.TemporaryDirectory() as d: