Read and control the house through Home Assistant (#256)

A `smarthome` block points Maven at a Home Assistant instance. She reads its
entity states to answer "что включено дома?", and every controllable device
becomes a PROPOSED row in the existing act allowlist — cmd
["smarthome",<entity_id>,<service>], scope smarthome:<domain> — so nothing new
had to be invented for the mutating half. ProposeTool/EnableTool/DisableTool,
tool.Matcher and the confirm turn are untouched; one branch in Executor.Exec
routes such a row to the client instead of exec, and "smarthome" is never run as
a binary. This is the same trick overnight/mcp-tools used for #251, on purpose.

Discovery only ever PROPOSES, and every control row is destructive=true: there
is no read-only way to turn the heating off, so flipping something in his flat
always costs a confirm turn and always had to be enabled by hand on /tools,
behind step-up.

The entity and the service come from the row he enabled, never from the
utterance — Exec drops the spoken tail for a house row. A router that misheard
can pick the wrong lamp; it cannot compose a target of its own. The service is
checked against the domain's table on the way out too, so a hand-edited cmd
column cannot reach an arbitrary Home Assistant service. set_brightness and
set_temperature are deliberately absent: a spoken number the router got wrong is
a wrong act on real hardware, and on/off is the whole of what a voice turn can
defend.

The read side is a query source ("home", before calendar and the recall passes)
so "что нового дома?" is not answered from an old note. Its matcher needs a
house marker plus an ask plus a device word and bails out on weather wording,
because "какая температура на улице?" belongs to the weather source.

Off unless configured: the block is dark without "enabled": true, and
applyDefaults normalises a disabled block to nil so "off" stays in one place.
deploy/mavend.json carries it disabled, with the token as ${HA_TOKEN}.

NOT shipped, and not faked: MQTT / Zigbee2MQTT (plan steps 2 and 5) and the
sensor-to-fact and presence-probe pipelines. There is no broker and no Home
Assistant anywhere on this network — 8123 and 1883 are closed on every host in
192.168.1.0/24 — the module tree is vendored so a paho dependency cannot be
added offline, and Home Assistant already fronts Zigbee2MQTT where it exists.
Writing a sensor pipeline with no sensor to test it against would be a guess.

Vikunja #256

deploy/mavend.json

@@ -45,6 +45,17 @@
     ]
   },
 
+  "smarthome": {
+    "provider": "homeassistant",
+    "url": "http://192.168.1.50:8123",
+    "token": "${HA_TOKEN}",
+    "domains": ["light", "switch", "sensor"],
+    "max_entities": 40,
+    "timeout": "10s",
+    "refresh": "15m",
+    "enabled": false
+  },
+
   "nexus":  { "url": "http://nexus:9740" },
   "praxis": { "url": "http://praxis:8989" },
   "hexis":  { "url": "http://hexis:9741" },