feat(oxibadge): add month-confirmation flow and fetch records/employees

Adds the screen after onboarding: pick a month/year (ConfirmMonth), show
loading screens while the device is queried, then download that month's
records and resolve each distinct employee's name, printing both to
stdout (debug pretty-print) before landing on the placeholder "done"
screen.

- r701: RecordIterator's boxed stream is now Send, required for it to
  cross into a Tauri command's future.
- oxibadge: load_records/load_employees commands, sharing the existing
  3-retry connect_with_retries helper. load_records uses skip_while/
  take_while on the device's newest-first stream to grab only the
  target month without walking its whole history, then a single
  collect + in-place Vec::reverse() back to chronological order.
- Shared LoadingScreen/Intro components extracted so future screens
  reuse the same look without duplicating markup/CSS.

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

oxibadge/src/lib/components/Onboarding.svelte

@@ -2,6 +2,7 @@
   import { invoke } from '@tauri-apps/api/core';
   import { _ } from 'svelte-i18n';
   import Column from './Column.svelte';
+  import Intro from './Intro.svelte';
   import Field from './Field.svelte';
   import Button from './Button.svelte';
   import ErrorBanner from './ErrorBanner.svelte';
@@ -48,10 +49,7 @@
 </script>
 
 <Column>
-  <header class="intro">
-    <h1>{$_('onboarding.title')}</h1>
-    <p>{$_('onboarding.subtitle')}</p>
-  </header>
+  <Intro title={$_('onboarding.title')} subtitle={$_('onboarding.subtitle')} />
 
   <form
     class="form"
@@ -96,32 +94,6 @@
 </Column>
 
 <style>
-  .intro {
-    display: flex;
-    flex-direction: column;
-    align-items: center;
-    gap: 12px;
-    text-align: center;
-  }
-
-  h1 {
-    margin: 0;
-    font-family: var(--ox-font-display);
-    font-weight: 700;
-    font-size: 48px;
-    line-height: 1.05;
-    letter-spacing: -0.03em;
-    color: var(--ox-text-strong);
-  }
-
-  .intro p {
-    margin: 0;
-    max-width: 340px;
-    font-size: 15px;
-    line-height: 1.5;
-    color: var(--ox-text-muted);
-  }
-
   .form {
     display: flex;
     flex-direction: column;