MAINT-11: start or stop the maintenance cycle per battery

maint_start and maint_abort take an optional unit. With two or more batteries
each Batteries card has Start cycle and Stop cycle buttons. One slot per site
stays: a start while a battery cycles is refused and names it (no queue). A
battery that is switched off, an unknown unit, and a stop on a battery that is
not cycling are refused with a plain message. A request with no unit is the
old call. The scheduler and the phase machine are unchanged.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/app/web.py

@@ -60,6 +60,8 @@ _LOG = logging.getLogger("goodwe.web")
 
 # OPT-11: the per-battery actions, which name a battery and a value.
 PACK_ACTIONS = ("pack_use", "pack_mode", "pack_sell")
+# MAINT-11: start or stop one battery's maintenance cycle (the unit is optional).
+MAINT_ACTIONS = ("maint_start", "maint_abort")
 
 # UX-13 P1: the page lives in app/static/ as three files - index.html,
 # app.css, app.js - plus the page words from app/ui_text/<lang>.json (English
@@ -163,6 +165,14 @@ def build_app(controller, selfcfg=None) -> web.Application:
                 return web.json_response({"ok": False,
                                           "error": result["error"]},
                                          status=400)
+        elif what in MAINT_ACTIONS and body.get("unit") is not None:
+            # MAINT-11: one battery's cycle. No unit = the old bare call below.
+            result = await controller.handle_action(what, unit=body["unit"])
+            if isinstance(result, dict) and "error" in result:
+                return web.json_response(
+                    {"ok": False, "error": result["error"],
+                     "code": result["code"], "unit": result["unit"]},
+                    status=409 if result["code"] != "unit" else 400)
         else:
             result = await controller.handle_action(what)
         if result is None: