feat: standardize input styling with tier system, add depth and admin features

- Define 4 input tier CSS classes (input-standard, input-search, input-embedded, input-danger)
  in globals.css, migrating ~50 inputs across ~28 component files to use them
- Add subtle border and inset shadow to solid input tiers for resting-state visibility
- Fix focus ring clipping in settings panel scroll container
- Fix phantom Tailwind tokens (border-border-primary, placeholder-txt-muted)
- Add admin user management panel, storage management, and account deletion utilities

packages/web/src/components/modals/instanceSettingsPanels/GeneralPanel.tsx

@@ -56,7 +56,7 @@ export function GeneralPanel() {
             value={draft.instanceName}
             onChange={(e) => setDraft({ ...draft, instanceName: e.target.value.slice(0, 32) })}
             placeholder="Backspace"
-            className="w-full px-3 py-2 bg-surface-input rounded text-sm text-txt-primary outline-none focus:ring-1 focus:ring-accent-primary placeholder:text-txt-tertiary"
+            className="input-standard w-full"
           />
           <div className="text-[11px] text-txt-tertiary text-right mt-1">{draft.instanceName.length}/32</div>
         </div>