SMA-10: two idle states, hold 0 W or hand the inverter back

A driver now says whether its release() hands the inverter back
(Driver.hands_back; GoodWe is False, so release() stays write(0) and the
Controller never calls it). command_site_release() sits next to
command_site_zero(): the Stop button and shutdown() (so SIGTERM, restart,
control task death and a late config refusal) hand a hand-back unit back,
once, and zero every other unit as before. Safety stops and refusals still
hold 0 W for every unit. Shadow mode releases a hand-back unit. After a
release nothing is written to the unit (heartbeat and cycle included) until
control starts again. release() is bounded by RELEASE_BUDGET_S (= the write
budget), runs concurrently per unit, and a raising or hanging release on one
unit does not stop the others.

The "set to 0 W" sentences for Stop, restart, shadow mode and the stopped
banner are built from the roster (app/handback.py, EN and NL, words from the
driver); a GoodWe-only roster keeps every old literal. A handed-back unit
shows "Back under <its control>" on Home.

Existing test edited: test_messages.py (two classification entries for the
CRITICAL line that moved into a roster builder, and the new release bound).

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

goodwe_controller/app/uitext.py

@@ -13,6 +13,11 @@ import os
 DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "ui_text")
 LANGS = ("en", "nl")
 _CACHE: dict = {}
+# SMA-10. The sentences that move with the roster (handback.overlay): empty for
+# every GoodWe-only roster, and then `raw()` is the file as it always was.
+_IDLE: dict = {}
+_GEN = [0]
+_MERGED: dict = {}
 
 
 def lang_of(value) -> str:
@@ -21,14 +26,36 @@ def lang_of(value) -> str:
     return head if head in LANGS else "en"
 
 
-def raw(lang: str) -> dict:
-    """One language file as written, without the English fallback."""
+def _file(lang: str) -> dict:
     if lang not in _CACHE:
         with io.open(os.path.join(DIR, f"{lang}.json"), encoding="utf-8") as f:
             _CACHE[lang] = json.load(f)
     return _CACHE[lang]
 
 
+def set_idle(overlay: dict) -> None:
+    """SMA-10: the roster-built sentences, `{lang: nested dict}` (or {})."""
+    _IDLE.clear()
+    _IDLE.update(overlay or {})
+    _MERGED.clear()
+    _GEN[0] += 1
+
+
+def generation() -> int:
+    """Changes whenever `set_idle()` does, so a cache of words can tell."""
+    return _GEN[0]
+
+
+def raw(lang: str) -> dict:
+    """One language file as written, without the English fallback (and with the
+    roster's own sentences laid over it when a unit is handed back)."""
+    if lang not in _IDLE:
+        return _file(lang)
+    if lang not in _MERGED:
+        _MERGED[lang] = _merge(_file(lang), _IDLE[lang])
+    return _MERGED[lang]
+
+
 def _merge(base, over):
     if not (isinstance(base, dict) and isinstance(over, dict)):
         return copy.deepcopy(over)