fix(ui): resolve light-theme low-contrast semantic text app-wide (#1909)

The app was built dark-first, so hundreds of hardcoded Tailwind semantic
text/icon utilities at light shades (text-amber-400, text-blue-300, ...) had
no dark: variant. With darkMode:'class' they applied in light theme too,
producing washed-out text on pale tints and white cards — including the three
reported spots (AMS Drying banner, Archives no-3MF warning, debug-logging
banner). Give each a theme-aware pair: a darker readable shade in light theme
with the original pinned to dark:, so dark theme is unchanged. ~100 files.

The bambu-* CSS-variable palette (self-correcting) and the dark-only SpoolBuddy
kiosk are left untouched. Plain text-white is already theme-aware via the
existing index.css .text-white override, so it needed no changes.

frontend/src/components/SpoolFormModal.tsx

@@ -817,7 +817,7 @@ export function SpoolFormModal({
         {mode === 'create' && (
           <div className="flex items-center justify-between px-4 py-2 border-b border-bambu-dark-tertiary flex-shrink-0">
             <div className="flex items-center gap-2">
-              <Zap className="w-4 h-4 text-amber-400" />
+              <Zap className="w-4 h-4 text-amber-600 dark:text-amber-400" />
               <span className="text-sm text-white">{t('inventory.quickAdd')}</span>
             </div>
             <button
@@ -880,7 +880,7 @@ export function SpoolFormModal({
               {spoolmanMode && !isEditing && (
                 <div>
                   {filamentsError ? (
-                    <p className="text-sm text-red-400 px-1">{t('inventory.spoolmanCatalogLoadFailed')}</p>
+                    <p className="text-sm text-red-700 dark:text-red-400 px-1">{t('inventory.spoolmanCatalogLoadFailed')}</p>
                   ) : (
                     <SpoolmanFilamentPicker
                       filaments={spoolmanFilaments}