fix(redesign): a11y, mobile, perf polish for production push

Comprehensive pre-production sweep across the Aurora redesign — drives
svelte-check to 0 errors / 0 warnings (was 61) without changing visual
intent. Highlights:

- Mobile: hero title shrinks at 480px, signal-list stacks timestamp
  under sentence below 640px, sidebar icon buttons bumped to 40x40
- Light theme: muted-foreground darkened to #3a3560 to clear WCAG AA
  on glass surfaces and the modal close button
- Perf: topbar backdrop-filter 28→14px, mobile-more sheet 28→12px to
  cut concurrent blur layers on mid-tier mobile
- a11y: prefers-reduced-motion mute for aurora drift / pulses /
  shimmer / stagger; aria-label on every icon-only button;
  aria-describedby on Hint; combobox/listbox/aria-activedescendant on
  SearchPalette; modal dialog tabindex; 47 label-without-control
  warnings across 14 form pages cleaned up via for=/id= or label→div
- Dashboard derived state split into topology- vs status-bound layers
  so polling no longer re-runs the full provider/wires computation
- Mobile bottom nav derived from baseNavEntries by key lookup so
  adding a top-level nav entry keeps the two trees in sync
- Bug: template-configs page now respects the global provider filter
  for both the count meter and the type pill (was reading the
  unfiltered cache)
- Misc: portal EventChart tooltip and switch its swatches to Aurora
  tokens; CollapsibleSlot warning state uses warning-fg/-bg tokens
  instead of #d97706; Hint z-index 99999→9999; element refs across
  Modal/EntitySelect/MultiEntitySelect/SearchPalette/IconGridSelect/
  Hint/targets converted to \$state for reactivity; 4 dead
  .topbar-cta selectors removed

frontend/src/routes/template-configs/+page.svelte

@@ -219,7 +219,7 @@
 
 	const headerPills = $derived.by(() => {
 		const pills: Array<{ label: string; tone: 'sky' }> = [];
-		const types = new Set(allTemplateConfigs.map(c => c.provider_type)).size;
+		const types = new Set(configs.map(c => c.provider_type)).size;
 		if (types > 0) pills.push({ label: `${types} ${types === 1 ? t('providers.typeSingular') : t('providers.typePlural')}`, tone: 'sky' });
 		return pills;
 	});
@@ -400,7 +400,7 @@
 	emphasis={t('templateConfig.titleEmphasis')}
 	description={t('templateConfig.description')}
 	crumb="Routing · Notification"
-	count={allTemplateConfigs.length}
+	count={configs.length}
 	countLabel={t('templateConfig.countLabel')}
 	pills={headerPills}
 >
@@ -432,7 +432,7 @@
 
 		{#if !editing}
 		<div>
-			<label class="block text-sm font-medium mb-1">{t('templateConfig.providerType')}</label>
+			<div class="block text-sm font-medium mb-1">{t('templateConfig.providerType')}</div>
 			<IconGridSelect items={providerTypeItems()} bind:value={form.provider_type} columns={2} />
 		</div>
 		{:else}
@@ -443,7 +443,7 @@
 		{/if}
 
 		<div class="flex items-center gap-2">
-			<label class="text-sm font-medium">{t('templateConfig.previewAs')}:</label>
+			<span class="text-sm font-medium">{t('templateConfig.previewAs')}:</span>
 			<IconGridSelect items={previewTargetTypeItems()} bind:value={previewTargetType} columns={2} />
 		</div>
 
@@ -484,9 +484,9 @@
 						{#if slot.isDateFormat}
 							<div>
 								<div class="flex items-center justify-between mb-1">
-									<label class="text-xs text-[var(--color-muted-foreground)]">{slot.description || t(`templateConfig.${slot.label}`, slot.label)}</label>
+									<label for="datefmt-{slot.key}" class="text-xs text-[var(--color-muted-foreground)]">{slot.description || t(`templateConfig.${slot.label}`, slot.label)}</label>
 								</div>
-								<input value={(form as any)[slot.key]}
+								<input id="datefmt-{slot.key}" value={(form as any)[slot.key]}
 									oninput={(e: Event) => { (form as any)[slot.key] = (e.target as HTMLInputElement).value; clearTimeout(validateTimers['_fmt']); validateTimers['_fmt'] = setTimeout(refreshAllPreviews, 600); refreshDateFormatPreview(); }}
 									class="w-full px-2 py-1 border border-[var(--color-border)] rounded-md text-sm bg-[var(--color-background)] font-mono" />
 								{#if dateFormatPreview[slot.key]}
@@ -532,7 +532,7 @@
 
 								{#if slotErrors[slot.key]}
 									{#if slotErrorTypes[slot.key] === 'undefined'}
-										<p class="mt-1 text-xs" style="color: #d97706;">⚠ {t('common.undefinedVar')}: {slotErrors[slot.key]}</p>
+										<p class="mt-1 text-xs" style="color: var(--color-warning-fg);">⚠ {t('common.undefinedVar')}: {slotErrors[slot.key]}</p>
 									{:else}
 										<p class="mt-1 text-xs" style="color: var(--color-error-fg);">✕ {t('common.syntaxError')}: {slotErrors[slot.key]}{slotErrorLines[slot.key] ? ` (${t('common.line')} ${slotErrorLines[slot.key]})` : ''}</p>
 									{/if}