v1.5.5 - user presets, recording indicator, screenshot folder

v1.5.5 - user presets, recording indicator, screenshot folder

User presets

• Save preset snapshots the current slider values (Intensity / Local tone / Local structure / Skin structure) under a name - it appears in the Profile list and applies like a built-in profile. Delete preset removes the active user preset.
• The config is user-editable, so everything is hardened: broken preset entries are dropped, a config pointing at a deleted preset falls back to Natural instead of crashing.

Recording indicator

• While a recording runs, a red dot with a timer sits in the corner of the screen (opaque badge, hidden from the recorded file). Toggle in Settings -> Behaviour.

Screenshot folder (issue #20)

• Screenshot folder... in Settings remembers a folder; the Save As dialog then opens there every time.

UI

• The resolution slider got its own section (RESOLUTION) instead of hiding under Speed.
• Expanded profile/language lists are a pop-up layer: soft edge gradient, hover highlights the row. The window list highlights the row on hover too.
• Alerts for silent failure points: failed screenshot, incomplete recording, failed config write (preset/hotkey rollback).

Under the hood

• Swappable runtime: nr_dll in config.json (or NS_NR_DLL env) loads a different nvngx_dlssnr.dll build without rebuilding the worker.
• MV validation: noise-floor motion vectors are zeroed (sharper static text/UI).
• Environment header in the log: version, Windows, HDR, driver, Num Lock, language.
• Fix: black window after a profile change in one-window mode.
• Fix: crash when scrolling the expanded language list.

49 tests green (two full runs), 12 languages, 97 keys each.