feat(oxibadge): add settings screen for shifts, rounding and language

Add a settings screen (gear button on the month-confirmation screen)
to configure the expected shift times, the rounding step, the
interface language, and the time clock address — replacing the old
onboarding-only connection flow. Settings persist to the same
preferences.toml as the reader address, under a single load_settings/
save_settings command pair.

The review screen's "fix shifts" action now redistributes stacked
punches by nearest configured shift time instead of blind position,
and a stacked cell manually cleared down to one entry no longer
leaves a dangling empty input.

Assisted-by: Claude Sonnet 5 <noreply@anthropic.com>

oxibadge/src/lib/components/review/TimesheetTable.svelte

@@ -1,12 +1,14 @@
 <script lang="ts">
   import { _ } from 'svelte-i18n';
-  import { COLS_KEYS, LUNCH, type Row, cellClass, dayLabel, hm, isRnd, noteOf } from './analysis';
+  import type { Shifts } from '$lib/shifts';
+  import { COLS_KEYS, type Row, cellClass, dayLabel, hm, isRnd, noteOf } from './analysis';
   import FixButton from './FixButton.svelte';
 
   let {
     rows,
     rounded,
     emp,
+    shift,
     oncellinput,
     onfixday,
     onaddlunch,
@@ -15,6 +17,7 @@
     rows: Row[];
     rounded: Record<string, string>;
     emp: number;
+    shift: Shifts;
     oncellinput: (di: number, ci: number, ii: number, e: Event & { currentTarget: HTMLInputElement }) => void;
     onfixday: (di: number) => void;
     onaddlunch: (di: number) => void;
@@ -49,7 +52,7 @@
           0
         )}
         {@const manual = r.rowEdits - rnd}
-        {@const note = noteOf(r, rnd, manual, $_)}
+        {@const note = noteOf(r, rnd, manual, $_, shift.round_step_min)}
         {@const label = dayLabel(r)}
         <tr class:we={r.weekend} class:anom={!!r.issue}>
           <td class="first center"><span class="dow">{r.dow}</span><span class="mono">{r.di + 1}</span></td>
@@ -105,7 +108,7 @@
               {/if}
               {#if r.lunch}
                 <FixButton
-                  ariaLabel={$_('review.add_lunch_day_aria', { values: { start: LUNCH.start, end: LUNCH.end, label } })}
+                  ariaLabel={$_('review.add_lunch_day_aria', { values: { start: shift.out1, end: shift.in2, label } })}
                   onclick={() => onaddlunch(r.di)}
                 >
                   {#snippet icon()}
@@ -113,7 +116,7 @@
                       ><path d="M7 3v8M5 3v4a2 2 0 0 0 4 0V3M7 11v10M17 21V3c-2 1-3 3.5-3 7h3" /></svg
                     >
                   {/snippet}
-                  {$_('review.lunch_short')} <span class="mono">{LUNCH.start}–{LUNCH.end}</span>
+                  {$_('review.lunch_short')} <span class="mono">{shift.out1}–{shift.in2}</span>
                 </FixButton>
               {/if}
               {#if r.info}