Make Best one network, and retire Medium and the mixture

Best was a mixture of two experts and a gate, 110 GMAC a megapixel;
Medium a single network at 48 that was softer on real edges. fb-combo
(darkroom-denoise, 20 000 steps from fb-edges2, taught by the mixture
with a quarter of its crops from the edge-rich parts of the frames) is
Medium's shape and holds the mixture's edges on real photographs:
edge PSNR within 0.04-0.06 dB at ISO 1600/6400/25600, more sharpness
kept at all three, the chart's edge 0.89 photosites wide against 0.82.
It is 0.27 dB short on smooth areas at ISO 25600. It becomes Best, and
the methods are Bilinear, Fast and Best.

Saved edits keep their numbers: 2, which was Medium, is now Best, and
3, which was Best, is past the end and reads as the default, Best.
The network ships as mosaic-hq, a new name: the result cache keys a
model by name and size, and this one is byte for byte the old Medium's
size. Its tablet form (A16W16) lost 0.00 dB in simulated QDQ at every
ISO and at most 0.09 dB across the noise bracket.

core/dr-denoise/examples/denoise_raw.rs

@@ -2,7 +2,7 @@
 //!
 //! ```sh
 //! DARKROOM_ORT_DIR=~/.local/share/darkroom/runtime \
-//!     cargo run --release -p dr-denoise --features native --example denoise_raw -- IMG.CR2 out [fast|medium|best]
+//!     cargo run --release -p dr-denoise --features native --example denoise_raw -- IMG.CR2 out [fast|best]
 //! ```
 //!
 //! Decode, the app's hot-pixel pass, the frame's noise from its best source,
@@ -11,7 +11,7 @@
 //! camera RGB — for comparison with the training repo's own path
 //! (`tools/compare_rust.py` in darkroom-denoise). `DARKROOM_ORT_DIR` points
 //! at an ONNX Runtime build; the engine's cache goes to `DR_ENGINE_CACHE` or
-//! a temporary directory. The whole-frame network (`mosaic-best.onnx` beside
+//! a temporary directory. The whole-frame network (`mosaic-hq.onnx` beside
 //! the fixed file) runs where the rung takes any size; `DR_PLAN=tiles` keeps
 //! the 1408² tiles anyway, to compare the two.
 
@@ -25,15 +25,14 @@ fn main() {
     env_logger::Builder::from_env(env_logger::Env::default().default_filter_or("warn")).init();
     let mut args = std::env::args().skip(1);
     let (Some(input), Some(out)) = (args.next(), args.next()) else {
-        eprintln!("usage: denoise_raw RAW OUT_PREFIX [fast|medium|best]");
+        eprintln!("usage: denoise_raw RAW OUT_PREFIX [fast|best]");
         std::process::exit(2);
     };
     let shipped = match args.next().as_deref() {
         None | Some("best") => dr_denoise::BEST,
-        Some("medium") => dr_denoise::MEDIUM,
         Some("fast") => dr_denoise::FAST,
         Some(other) => {
-            eprintln!("no network called {other}: fast, medium or best");
+            eprintln!("no network called {other}: fast or best");
             std::process::exit(2);
         }
     };