Refactor extra1 to fertilizer_pump in HAL and main logic

- Renamed `extra1` method and related calls to `fertilizer_pump` for clarity and better domain alignment.
- Updated HAL implementation to control `extra2` GPIO for fertilizer pump operations.
- Added build script trigger to refresh `VERGEN_BUILD_TIMESTAMP` on each build.

Software/MainBoard/rust/build.rs

@@ -49,5 +49,8 @@ fn linker_be_nice() {
 
 fn main() {
     linker_be_nice();
+    // Non-existent path causes Cargo to always re-run this script,
+    // keeping VERGEN_BUILD_TIMESTAMP fresh on every build.
+    println!("cargo:rerun-if-changed=ALWAYS_REBUILD_SENTINEL");
     let _ = EmitBuilder::builder().all_git().all_build().emit();
 }

Software/MainBoard/rust/src/hal/mod.rs

@@ -164,7 +164,7 @@ pub trait BoardInteraction<'a> {
     async fn get_mptt_voltage(&mut self) -> FatResult<Voltage>;
     async fn get_mptt_current(&mut self) -> FatResult<Current>;
     async fn can_power(&mut self, state: bool) -> FatResult<()>;
-    async fn extra1(&mut self, enable: bool) -> FatResult<()>;
+    async fn fertilizer_pump(&mut self, enable: bool) -> FatResult<()>;
 
     async fn backup_config(&mut self, config: &PlantControllerConfig) -> FatResult<()>;
     async fn read_backup(&mut self) -> FatResult<PlantControllerConfig>;

Software/MainBoard/rust/src/hal/v4_hal.rs

@@ -484,11 +484,11 @@ impl<'a> BoardInteraction<'a> for V4<'a> {
         Ok(())
     }
 
-    async fn extra1(&mut self, enable: bool) -> FatResult<()> {
+    async fn fertilizer_pump(&mut self, enable: bool) -> FatResult<()> {
         if enable {
-            self.extra1.set_high();
+            self.extra2.set_high();
         } else {
-            self.extra1.set_low();
+            self.extra2.set_low();
         }
         Ok(())
     }

Software/MainBoard/rust/src/main.rs

@@ -733,9 +733,9 @@ pub async fn do_secure_pump(
                     &elapsed_minutes.to_string(),
                     "",
                 );
-                board.board_hal.extra1(true).await?;
+                board.board_hal.fertilizer_pump(true).await?;
                 Timer::after_millis(plant_config.fertilizer_s as u64 * 1000).await;
-                board.board_hal.extra1(false).await?;
+                board.board_hal.fertilizer_pump(false).await?;
                 info!("Fertilizer pump stopped");
 
                 // Store the current time as last fertilizer time

Software/MainBoard/rust/src/webserver/post_json.rs

@@ -109,9 +109,9 @@ where
     T: Read + Write,
 {
     let mut board = BOARD_ACCESS.get().await.lock().await;
-    board.board_hal.extra1(true).await?;
+    board.board_hal.fertilizer_pump(true).await?;
     embassy_time::Timer::after_millis(1000).await;
-    board.board_hal.extra1(false).await?;
+    board.board_hal.fertilizer_pump(false).await?;
     Ok(None)
 }