Implement MODE command support for channel modes

[ValwareIRC]

This PR adds comprehensive mode support for IRC channels, including ban lists, exception lists, invite lists, and mode management tools.

Summary by CodeRabbit

• New Features

  • Draggable Server Notices with JSON deep-dive, Link Security warnings, Channel Settings, Moderation and Invite modals, GIF picker, Whisper messages, User Profile modal, join-from-invite.

• UI/UX

  • Channel avatars & display names, drag‑and‑drop channel reordering, server mention badges, inline topic editing, smooth scroll-to-reply with highlight, improved image/GIF handling (Tenor/GIPHY resolution) and expired-image badge, draggable/minimizable server-notices popup.

• Preferences

  • Per-server link-security skip options, global show-kicks toggle, and notification volume control.

• Documentation

  • README Features section and screenshot updated.