refactor: move firmware workspace under firmware

firmware/libs/kaptan-sensor/src/range.rs

@@ -0,0 +1,26 @@
+//! Distance sensor observations.
+
+use kaptan_time::Timestamp;
+
+/// Coherent range observation in the sensor frame.
+///
+/// The timestamp is captured when the measurement is requested. Distance is
+/// expressed in millimetres so rangefinders with centimetre resolution can be
+/// published without floating-point conversion.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct RangeSnapshot {
+    /// Monotonic timestamp captured when the acquisition was requested.
+    pub timestamp: Timestamp,
+    /// Measured distance in millimetres.
+    pub distance_millimetres: u32,
+}
+
+impl RangeSnapshot {
+    /// Creates one accepted range observation.
+    pub const fn new(timestamp: Timestamp, distance_millimetres: u32) -> Self {
+        Self {
+            timestamp,
+            distance_millimetres,
+        }
+    }
+}