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/StreamingPanel.tsx

@@ -142,7 +142,7 @@ export function StreamingPanel() {
                   const v = Number(e.target.value);
                   if (v >= 50 && v <= 5000) setDraft({ ...draft, bitrateStepKbps: v });
                 }}
-                className="w-24 px-2 py-1 bg-surface-input rounded text-sm text-txt-primary outline-none focus:ring-1 focus:ring-accent-primary"
+                className="input-standard w-24 px-2 py-1"
               />
               <span className="text-[12px] text-txt-tertiary">kbps</span>
             </div>