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

internal/tool/tool.go

@@ -13,6 +13,11 @@
 //   - Args are passed as argv, NEVER through a shell. STT text lands as
 //     positional arguments to Cmd; there is no `sh -c`, so "restart nginx;
 //     rm -rf" can't inject — the tail is one argv element to the named binary.
+//   - An enabled row whose cmd is ["smarthome", "<entity_id>", "<service>"] is
+//     a Home Assistant service call instead of a process (Vikunja #256), by
+//     exactly the same trick and under exactly the same rules. Control rows are
+//     always destructive, so flipping something in his flat always costs a
+//     confirm turn.
 //   - An enabled row whose cmd is ["mcp", "<server>", "<tool>"] is a call to a
 //     configured MCP server instead of a process (Vikunja #251). It goes
 //     through every rule above unchanged — enabled, and confirmed if it
@@ -38,6 +43,7 @@ import (
 	"github.com/kami/maven/internal/ipc"
 	"github.com/kami/maven/internal/mcp"
 	"github.com/kami/maven/internal/router"
+	"github.com/kami/maven/internal/smarthome"
 )
 
 // API — the narrow slice of ipc.CoreAPI the executor and matcher need. Backed
@@ -64,6 +70,14 @@ type MCPCaller interface {
 	CallPositional(ctx context.Context, server, tool string, args []string) (string, error)
 }
 
+// HomeCaller is the seam for an act that is a Home Assistant service call
+// rather than a process (Vikunja #256). internal/smarthome.Client satisfies it.
+// nil ⇒ the house is not configured, and a house row refuses to run rather than
+// silently doing nothing.
+type HomeCaller interface {
+	CallService(ctx context.Context, entityID, service string) (string, error)
+}
+
 // Executor runs enabled tools. run is the exec seam (default: real process);
 // tests swap it. timeout bounds each invocation.
 type Executor struct {
@@ -71,6 +85,7 @@ type Executor struct {
 	timeout time.Duration
 	run     func(ctx context.Context, argv []string) (string, error)
 	mcp     MCPCaller
+	home    HomeCaller
 }
 
 // NewExecutor builds the executor. timeout<=0 defaults to 30s.
@@ -88,6 +103,14 @@ func (e *Executor) WithMCP(m MCPCaller) *Executor {
 	return e
 }
 
+// WithHome attaches the Home Assistant caller. Called once at wiring time when
+// the smarthome block is enabled; without it, a row whose cmd is
+// ["smarthome", …] refuses.
+func (e *Executor) WithHome(h HomeCaller) *Executor {
+	e.home = h
+	return e
+}
+
 // Exec looks up name in the store and runs Cmd+args as argv (no shell).
 // confirmed=true is the second turn of a destructive act (the user said "да");
 // it bypasses the ErrNeedsConfirm gate. Non-enabled ⇒ ErrNotEnabled; a
@@ -117,6 +140,20 @@ func (e *Executor) Exec(ctx context.Context, name string, args []string, confirm
 		defer cancel()
 		return e.mcp.CallPositional(ctx, server, remote, args)
 	}
+	// A house row is a Home Assistant service call, not a process (Vikunja
+	// #256). Same story: enabled, and confirmed — every control row is
+	// destructive, because there is no read-only way to turn the heating off.
+	// The spoken args are dropped on purpose: the entity and the service come
+	// from the row Kami enabled, so a router that misheard can pick the wrong
+	// row but can never compose a target of its own.
+	if entityID, service, ok := smarthome.ParseCmd(t.Cmd); ok {
+		if e.home == nil {
+			return "", ErrNotEnabled
+		}
+		ctx, cancel := context.WithTimeout(ctx, e.timeout)
+		defer cancel()
+		return e.home.CallService(ctx, entityID, service)
+	}
 	argv := append(append([]string(nil), t.Cmd...), args...)
 	if len(argv) == 0 {
 		return "", ErrNotEnabled