Core ride logic, FTMS client, FIT encoder and probe CLI

Adds backing state for Resistance and Erg control modes, which had no
value to hold and so could never satisfy FR-4.3/FR-4.6.

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

crates/ble/src/lib.rs

@@ -1 +1,70 @@
 //! FTMS client and BLE transport. See REQUIREMENTS.md §5.1–5.2.
+//!
+//! # Layout
+//!
+//! The crate is split so that everything protocol-shaped is a pure function
+//! over bytes, and only [`client`] and [`scan`] touch a radio. That is what
+//! lets the whole wire format be tested without a trainer on the desk:
+//!
+//! | Module | Contents | Needs hardware |
+//! |--------|----------|----------------|
+//! | [`uuids`] | FTMS assigned numbers | no |
+//! | [`indoor_bike_data`] | `0x2AD2` decoder | no |
+//! | [`control_point`] | `0x2AD9` encoders and response decoding | no |
+//! | [`capabilities`] | `0x2ACC`/`0x2AD5`/`0x2AD6`/`0x2AD8` decoding, and the safety gate | no |
+//! | [`scan`] | discovery | yes |
+//! | [`client`] | the connection actor | yes |
+//!
+//! # Usage
+//!
+//! ```no_run
+//! use bikecontrol_ble::{FtmsClient, FtmsConfig, TrainerSelector};
+//! use bikecontrol_core::types::ControlTarget;
+//!
+//! # async fn example() -> Result<(), Box<dyn std::error::Error>> {
+//! let client = FtmsClient::connect(TrainerSelector::Any, FtmsConfig::default()).await?;
+//!
+//! let mut telemetry = client.telemetry();
+//! tokio::spawn(async move {
+//!     while let Ok(sample) = telemetry.recv().await {
+//!         println!("{:?} W", sample.power_w);
+//!     }
+//! });
+//!
+//! client.set_target(ControlTarget::Gradient { percent: 4.0 }).await?;
+//!
+//! // SAF-2: always leave the trainer at zero.
+//! client.shutdown().await?;
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! # Attribution
+//!
+//! The FTMS field ordering, scaling and control-point encodings are ported from
+//! [`obostjancic/smart-trainer-control`](https://github.com/obostjancic/smart-trainer-control),
+//! MIT licensed, Copyright (c) 2025 Ogi — a working Van Rysel D100 client
+//! (REQUIREMENTS.md §3.2). Per-module attribution notes mark where.
+
+pub mod capabilities;
+pub mod client;
+pub mod control_point;
+pub mod error;
+pub mod indoor_bike_data;
+pub mod scan;
+pub mod uuids;
+
+pub use capabilities::{
+    FitnessMachineFeature, InclinationRange, PowerRange, ResistanceLevelRange, TrainerCapabilities,
+    UnsupportedTarget,
+};
+pub use client::{
+    safety_reset_commands, Backoff, ControlOutcome, FtmsClient, FtmsConfig, FtmsEvent, Procedure,
+};
+pub use control_point::{ControlPointResponse, OpCode, ResultCode, SimulationParameters, StopOrPause};
+pub use error::FtmsError;
+pub use indoor_bike_data::{DecodeError, IndoorBikeData};
+pub use scan::{
+    default_adapter, scan, scan_trainers, DiscoveredDevice, ScanKind, TrainerSelector,
+};
+pub use uuids::FITNESS_MACHINE_SERVICE;