KEY-ZOOM: Cmd+= / Cmd+- / Cmd+0 zoom the photo, not egui's interface scale (#566)

egui's zoom_with_keyboard was left on, so at the end of every frame it took the
same keys as View ▸ Zoom In / Zoom Out / Zoom to Fit for its browser-style
interface zoom. On macOS the native menu bar got the keys first; on Windows and
Linux the whole UI scaled. theme::apply turns the option off for every context
(desktop, headless, tests).

Headless tests that pressed Cmd+Plus / Cmd+Minus to exercise the interface
zoom's viewport handling set the zoom factor directly; the CLI snapshot test
that did the same is dropped (the unit tests cover the mechanism). New
tests_zoom_keys.rs: the shortcuts step the photo zoom while the zoom factor
stays, and Ctrl+wheel over the photo zooms it in the Edit view.

apps/lightcraft-cli/tests/cli.rs

@@ -233,29 +233,6 @@ fn snapshot_script_failure_exits_non_zero() {
     assert_eq!((d.width, d.height), (320, 200));
 }
 
-#[test]
-fn snapshot_ui_zoom_keeps_requested_pixel_dimensions() {
-    let script = tmp("snap-ui-zoom.jsonl");
-    std::fs::write(
-        &script,
-        format!("{}\n{}\n", json!({"method": "ui.key", "params": {"key": "Plus", "cmd": true}}), json!({"method": "ui.inspect"})),
-    )
-    .unwrap();
-    for (size, scale, expected) in [("400x240", "1", (400, 240)), ("345x200", "0.9", (311, 180))] {
-        let out = tmp(&format!("snap-ui-zoom-{scale}.png"));
-        let o = Command::new(BIN)
-            .args(["snapshot", "--script", script.to_str().unwrap(), "-o", out.to_str().unwrap(), "--size", size, "--scale", scale])
-            .output()
-            .unwrap();
-        assert!(o.status.success(), "{}", String::from_utf8_lossy(&o.stderr));
-        let replies: Vec<Value> = String::from_utf8_lossy(&o.stdout).lines().map(|line| serde_json::from_str(line).unwrap()).collect();
-        assert!(replies.iter().all(|reply| reply["ok"] == true), "{replies:?}");
-        assert!(replies[1]["result"]["pixelsPerPoint"].as_f64().unwrap() > scale.parse::<f64>().unwrap());
-        let decoded = lightcraft_codecs::decode(&std::fs::read(out).unwrap(), Default::default()).unwrap();
-        assert_eq!((decoded.width, decoded.height), expected);
-    }
-}
-
 /// Headless snapshots default to CPU photo rendering as well as CPU UI rasterization.
 #[test]
 fn snapshot_defaults_to_cpu_without_gpu_environment_overrides() {