fix(settings): a lingering inline range error stays visible after Reset settings or a reload because programmatic value sets do not re-run the validator #642

Found in the review of PR #634 (inline error for an empty global coverage field, merged). The validators from wireInlineRangeValidation only run on the input and blur events, but loadGlobalSettings (frontend/src/settings.ts ~3197) and resetSettings (~3718) set the field value programmatically without firing input, so a lingering error (now easier to reach with an EMPTY coverage field, which is flagged) stays visible with aria-invalid after Reset settings or a reload. Out-of-range values already behaved this way. Also: no test pins that 0 stays a valid coverage value (valid by reading: raw '0' is not '' and 0 is within 0..100).

Acceptance: after a programmatic set (load or reset) the validator re-runs (dispatch input after the sets, or have check() listen to a custom event) and the error clears; jest tests for reset-clears-error and for 0 valid. Frontend tests cannot run offline: wait for CI (Build frontend, Unit Tests). Related: #522, #634.