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/chat/MessageInput.tsx

@@ -349,7 +349,7 @@ export function MessageInput({ channelId, channelName }: MessageInputProps) {
             onKeyDown={handleKeyDown}
             onPaste={canAttachFiles ? handlePaste : undefined}
             placeholder={`Message ${channelName.startsWith('@') ? channelName : `#${channelName}`}`}
-            className="flex-1 py-[10px] px-1 bg-transparent text-txt-primary placeholder-txt-tertiary/60 outline-none resize-none text-[15px] leading-[1.375rem] max-h-[50vh] scrollbar-thin"
+            className="input-embedded flex-1 py-[10px] px-1 resize-none text-[15px] leading-[1.375rem] max-h-[50vh] scrollbar-thin"
             rows={1}
 
           />