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/ChannelSettingsModal.tsx

@@ -638,7 +638,7 @@ function PermissionsTab({
                   value={memberSearch}
                   onChange={(e) => setMemberSearch(e.target.value)}
                   placeholder="Search members..."
-                  className="w-full px-2.5 py-1.5 text-sm bg-surface-input rounded mb-1 text-txt-primary placeholder-txt-muted outline-none"
+                  className="input-search w-full mb-1"
                   autoFocus
                 />
               </div>