Remove 'type' field from discovery payload per HA spec

The type field is not required in the discovery payload JSON.
The entity type is determined by the discovery topic itself:
- homeassistant/sensor/.../config indicates a sensor
- homeassistant/switch/.../config indicates a switch

This aligns with the official Home Assistant MQTT discovery documentation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

pilot-v2/src/ha/mod.rs

@@ -19,8 +19,6 @@ struct DeviceInfo {
 #[derive(Serialize)]
 struct EntityConfig<'a> {
     name: &'a str,
-    #[serde(rename = "type")]
-    entity_type: &'a str,
     unique_id: String,
     state_topic: String,
     availability_topic: String,
@@ -69,7 +67,6 @@ pub async fn publish_all(client: &AsyncClient, cfg: &Config) -> Result<()> {
         let entity_name = format!("{}_{}", key, cfg.device.name);
         let entity = EntityConfig {
             name: &entity_name,
-            entity_type: "sensor",
             unique_id: format!("{}_{}", cfg.device.name, key),
             state_topic: format!("{}/{}", base, key),
             availability_topic: format!("{}/{}/available", base, key),
@@ -98,7 +95,6 @@ pub async fn publish_all(client: &AsyncClient, cfg: &Config) -> Result<()> {
         let entity_name = format!("{}_{}", key, cfg.device.name);
         let entity = EntityConfig {
             name: &entity_name,
-            entity_type: "switch",
             unique_id: format!("{}_{}", cfg.device.name, key),
             state_topic: format!("{}/{}/state", base, key),
             availability_topic: format!("{}/{}/available", base, key),