LR-PREF-SHORTCUTS: a declared shortcut yields to a key the saved keymap gives another command

When a saved keymap gave a key to one command and a later build declared
the same key as another command's default, one press ran both commands,
and menus and Help > Keyboard Shortcuts listed the key on both.

binding() now drops a declared shortcut while the keymap gives its key to
another known command, other than its contextual partner. handle(),
conflicts(), shortcut_of(), the menus and the shortcut editor read it.
In the editor such a row counts as changed, so its restore button takes
the key back.

handle() also let every saved entry stop the fixed keys on its key
(Enter in the grid, secondary keys such as Shift+X, the rating and
label digits, Home, End and Shift+arrows), including entries for
commands the build does not know. It now reads only the entries of
known commands, as binding() does, so a stale entry in ui.json no
longer silences Shift+X, a rating digit or a label digit.

docs/parity-checklist.md

@@ -437,7 +437,7 @@ differences and missing bindings are in [ui-parity.md](ui-parity.md#shortcuts).
 | LR-PREF-PERFORMANCE | GPU / performance | P1 | ✅ | `cmd:app.gpu`, `cmd:app.memoryBudget`, `cmd:app.settings` | GPU on/off (a crash while the GPU device or its kernels are built, issue #250, turns it off for the next launch), preview size (Automatic = the whole-frame loupe render at canvas size, up to 2560 px; or a 1600–5120 px size for it; zoomed views add a window at up to 100 %, issue #323), memory budget (a quarter of it is the idle per-view stage caches' share; the open photo's views are counted and reported, and cut only past four times that, the before side's and the zoom window's first — a Before/After at 1:1 on a 2800 px canvas holds about 1 GB of GPU stages, plus the one 288 MB copy of the original, which `ui.inspect` reports as `sharedSourceBytes`), thumbnail cache size in Settings |
 | LR-PREF-PEOPLE | Face recognition | P2 | 🟡 | `cmd:faces.enable`, `cmd:faces.models.list`, `cmd:faces.models.inspect`, `cmd:faces.models.install`, `cmd:faces.models.download`, `cmd:faces.models.downloads`, `cmd:faces.models.downloadCancel`, `cmd:faces.models.remove`, `cmd:faces.models.select`, `cmd:dialog.faceModel`, `crates/faces/src/lib.rs`, `crates/ui-egui/src/panels/faces.rs` | Settings ▸ Faces: an off-by-default toggle and the face model list. Models are opt-in and never bundled, the 232 KB YuNet detector included. Press Download (terms first; then a pinned address, size and SHA-256 checked, fetched over pure-Rust https with `lightcraft-fetch`), or add any `.onnx` by picking or dropping it: it is recognised by hash or described from its shape, shows its licence terms and training-data note, runs a self-test, and installs only after an "I accept" box; an installed model is chosen and recognition switched on at once (the newest wins, each model keeps its own embedding cache). Non-commercial models are add-by-file only, never offered for download. Suggestions of names run on the shared pure-Rust CPU interpreter (`crates/faces/src/net.rs`, `crates/faces/src/runtime.rs`; bounded im2col/GEMM, checked ONNX shapes/operators; no external inference runtime; 40 public crops agree within 2.1e-6, one-thread SFace 34–36 ms / AuraFace 233–252 ms, see docs/faces.md) in a background worker and are never applied automatically. Thresholds are starting points calibrated on busts, not yet on live faces; the Recognise faces switch is off until a recognition model is chosen and installed (`faces.enable {enabled: true}` refuses otherwise; removing the last recogniser switches it off), issue #678 |
 | LR-PREF-WATERMARK | Watermark settings | P1 | ✅ | `cmd:export.savePreset`, `crates/ui-egui/src/panels/dialogs.rs` | set in the Export dialog; kept with Export with Previous and in saved export presets |
-| LR-PREF-SHORTCUTS | Shortcut customisation | — | ✅ | `cmd:app.setShortcut`, `cmd:app.resetShortcuts`, `crates/ui-egui/src/panels/keymap.rs` | an extra (the reference app has no keymap editor): Help ▸ Keyboard Shortcuts (⌘/) lists every command; click a shortcut and press the new keys (Esc cancels), × removes, ↺ restores, Reset All; a key another command had moves over; saved in `ui.json`; native menu accelerators follow. Rating/label digits and secondary keys are listed read-only and yield to a key given to a command |
+| LR-PREF-SHORTCUTS | Shortcut customisation | — | ✅ | `cmd:app.setShortcut`, `cmd:app.resetShortcuts`, `crates/ui-egui/src/panels/keymap.rs` | an extra (the reference app has no keymap editor): Help ▸ Keyboard Shortcuts (⌘/) lists every command; click a shortcut and press the new keys (Esc cancels), × removes, ↺ restores, Reset All; a key another command had moves over; a declared key that `ui.json` already gives another command stays with that command until ↺ takes it back; saved in `ui.json`; native menu accelerators follow. Rating/label digits and secondary keys are listed read-only and yield to a key given to a command |
 | LR-PREF-TECHPREVIEW | Early-access toggles | P2 | ⬜ | | |
 | LR-PREF-NOTIFICATIONS | Notifications | OOS | 🚫 | | |
 | LR-PREF-DEVICE | Device settings | P2 | ⬜ | | |