feat(bridge): MQTT bridge with Home Assistant auto-discovery

pkg/bridge/helpers.go

@@ -0,0 +1,20 @@
+package bridge
+
+import "fmt"
+
+func (b *Bridge) availTopic() string { return b.cfg.BaseTopic + "/availability" }
+func (b *Bridge) stateTopic(out int) string {
+	return fmt.Sprintf("%s/output%d/state", b.cfg.BaseTopic, out)
+}
+func (b *Bridge) cmdTopic(out int) string {
+	return fmt.Sprintf("%s/output%d/set", b.cfg.BaseTopic, out)
+}
+func (b *Bridge) discoveryTopic() string {
+	return fmt.Sprintf("%s/device/ezcoo_matrix/config", b.cfg.DiscoveryPrefix)
+}
+func (b *Bridge) availPayload() string {
+	if b.available.Load() {
+		return "online"
+	}
+	return "offline"
+}