Adjust timeouts and constants for improved moisture sensor and backup management accuracy

- Increased CAN measurement timeout to 5000ms for reliability.
- Updated `SAVEGAME_SLOT_SIZE` usage in backup handling for consistency.
- Refined moisture sensor frequency thresholds for better sensor calibration (400Hz-70kHz).

Software/MainBoard/rust/src/plant_state.rs

@@ -4,8 +4,8 @@ use chrono::{DateTime, TimeDelta, Utc};
 use chrono_tz::Tz;
 use serde::{Deserialize, Serialize};
 
-const MOIST_SENSOR_MAX_FREQUENCY: f32 = 7500.; // 60kHz (500Hz margin)
-const MOIST_SENSOR_MIN_FREQUENCY: f32 = 150.; // this is really, really dry, think like cactus levels
+const MOIST_SENSOR_MAX_FREQUENCY: f32 = 70000.; // 70kHz
+const MOIST_SENSOR_MIN_FREQUENCY: f32 = 400.; // this is really, really dry, think like cactus levels
 
 #[derive(Debug, PartialEq, Serialize)]
 pub enum MoistureSensorError {
@@ -312,7 +312,7 @@ impl PlantState {
             },
             sensor_a_firmware_build_minutes: self.sensor_a_firmware_build_minutes,
             sensor_b_firmware_build_minutes: self.sensor_b_firmware_build_minutes,
-            last_fertilizer_time: self.last_fertilizer_time
+            last_fertilizer_time: self.last_fertilizer_time,
         }
     }
 }