Gearing as development, physics-derived load model, 105kg rider

Gears are metres per crank revolution rather than gradient offsets, and
resistive_force_n exposes what the road is doing at a given speed so load
can be computed directly instead of servoed.

The load model is tested but not yet commanded: FTMS sim mode has the
trainer compute rolling and aero itself, so sending a gradient that already
contains them would double-count. Needs Crr/Cw zeroed and a ride to verify.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

crates/ble/src/click.rs

@@ -57,7 +57,14 @@ pub enum ClickEvent {
         name: Option<String>,
     },
     /// The link dropped. Any held button has already been reported as released.
+    /// The actor is retrying — this is not terminal.
     Disconnected,
+    /// Reconnecting ran out of attempts and the actor has stopped (FR-1.11).
+    ///
+    /// Terminal, and distinct from [`ClickEvent::Disconnected`] for exactly that
+    /// reason: one means "hold on", the other means "go and look at the pod".
+    /// Nothing further arrives on this stream.
+    GaveUp { attempts: u32 },
     /// A press or release edge. Repeats while held are filtered out here, not
     /// by the consumer (see [`ButtonTracker`]).
     Button { button: Button, pressed: bool },