Switching presets now restores the user's prior edits to that preset
instead of factory defaults. Edits are stashed per preset name under
the quality_profile_presets preference; 'custom'/unknown names are not
stashed. Adds a /reset endpoint + "Reset to defaults" UI link to drop a
preset's saved edits.
- DB: set_quality_profile stashes per-preset; get_quality_preset returns
the customized form by default, _factory_quality_preset for the raw
defaults; reset_quality_preset forgets a preset's edits.
- web_server: apply-preset carries the global search_mode across switches;
new preset/<name>/reset endpoint.
- UI: target edits now save via debouncedSaveQualityProfile (profile-only,
no full settings re-init/flicker); preset switch suppresses the global
auto-save listener; help text + reset link.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>