feat: Phase 4 Aether Drift — auth, modals & UI component token migration

Migrate all auth pages, modals, and shared UI components from Discord
visual language to Aether Drift design tokens. Zero discord-* classes
or raw Tailwind palette colors remain in components/auth/, modals/, ui/.

- Avatar: status dots use status-online/idle/dnd/offline tokens
- Tooltip, ContextMenu, UserProfilePopout: z-index raised to z-[200]
- LoginPage, RegisterPage: warm bg-surface-base with lavender glow
- All modals: inputs use surface-input, buttons use accent-primary
- Toggles: bg-status-online (on), bg-surface-input (off)
- ServerSettings: slider tracks, pills, danger zone fully tokenized
- Purged raw Tailwind green-500 leak in StreamingLimitsPanel success msg

packages/web/src/components/modals/ChannelSettingsModal.tsx

@@ -92,10 +92,10 @@ export function ChannelSettingsModal() {
     <Modal isOpen={isOpen} onClose={closeModal} title="Channel Settings" maxWidth="max-w-md">
       <div className="space-y-4">
         <div>
-          <label className="block text-xs font-bold text-discord-text-secondary uppercase mb-2">
+          <label className="block text-xs font-bold text-txt-secondary uppercase mb-2">
             Channel
           </label>
-          <div className="flex items-center gap-2 text-discord-text-primary">
+          <div className="flex items-center gap-2 text-txt-primary">
             <svg width="20" height="20" viewBox="0 0 24 24" fill="currentColor" className="opacity-60 flex-shrink-0">
               <path d="M5.88657 21C5.57547 21 5.3399 20.7189 5.39427 20.4126L6.00001 17H2.59511C2.28449 17 2.04905 16.7198 2.10259 16.4138L2.27759 15.4138C2.31946 15.1746 2.52722 15 2.77011 15H6.35001L7.41001 9H4.00511C3.69449 9 3.45905 8.71977 3.51259 8.41381L3.68759 7.41381C3.72946 7.17456 3.93722 7 4.18011 7H7.76001L8.39677 3.41262C8.43914 3.17391 8.64664 3 8.88907 3H9.87344C10.1845 3 10.4201 3.28107 10.3657 3.58738L9.76001 7H15.76L16.3968 3.41262C16.4391 3.17391 16.6466 3 16.8891 3H17.8734C18.1845 3 18.4201 3.28107 18.3657 3.58738L17.76 7H21.1649C21.4755 7 21.711 7.28023 21.6574 7.58619L21.4824 8.58619C21.4406 8.82544 21.2328 9 20.9899 9H17.41L16.35 15H19.7549C20.0655 15 20.301 15.2802 20.2474 15.5862L20.0724 16.5862C20.0306 16.8254 19.8228 17 19.5799 17H16L15.3632 20.5874C15.3209 20.8261 15.1134 21 14.8709 21H13.8866C13.5755 21 13.3399 20.7189 13.3943 20.4126L14 17H8.00001L7.36325 20.5874C7.32088 20.8261 7.11337 21 6.87094 21H5.88657ZM9.41001 9L8.35001 15H14.35L15.41 9H9.41001Z" />
             </svg>
@@ -104,16 +104,16 @@ export function ChannelSettingsModal() {
         </div>
 
         {error && (
-          <div className="p-2 bg-discord-red/10 border border-discord-red/30 rounded text-discord-text-danger text-sm">
+          <div className="p-2 bg-accent-rose/10 border border-accent-rose/30 rounded text-txt-danger text-sm">
             {error}
           </div>
         )}
 
-        <div className="pt-2 border-t border-discord-bg-tertiary">
+        <div className="pt-2 border-t border-border-soft">
           <div className="flex items-center justify-between">
             <div>
-              <div className="text-sm font-medium text-discord-text-primary">Private Channel</div>
-              <div className="text-xs text-discord-text-muted mt-0.5">
+              <div className="text-sm font-medium text-txt-primary">Private Channel</div>
+              <div className="text-xs text-txt-tertiary mt-0.5">
                 Only selected members and roles will be able to view this channel.
               </div>
             </div>
@@ -122,10 +122,10 @@ export function ChannelSettingsModal() {
               disabled={isLoading || isFetching}
               className={`relative w-10 h-6 rounded-full transition-colors flex-shrink-0 ml-4 ${
                 isFetching
-                  ? 'bg-discord-bg-tertiary opacity-50 cursor-wait'
+                  ? 'bg-surface-input opacity-50 cursor-wait'
                   : isPrivate
-                    ? 'bg-discord-green'
-                    : 'bg-discord-bg-tertiary'
+                    ? 'bg-status-online'
+                    : 'bg-surface-input'
               } ${isLoading ? 'opacity-70 cursor-wait' : 'cursor-pointer'}`}
               aria-label={isPrivate ? 'Make channel public' : 'Make channel private'}
             >
@@ -139,8 +139,8 @@ export function ChannelSettingsModal() {
         </div>
 
         {isPrivate && !isFetching && (
-          <div className="flex items-start gap-2 p-2 bg-discord-bg-tertiary/50 rounded text-xs text-discord-text-muted">
-            <svg width="16" height="16" viewBox="0 0 24 24" fill="currentColor" className="flex-shrink-0 mt-0.5 text-discord-text-secondary">
+          <div className="flex items-start gap-2 p-2 bg-surface-input/50 rounded text-xs text-txt-tertiary">
+            <svg width="16" height="16" viewBox="0 0 24 24" fill="currentColor" className="flex-shrink-0 mt-0.5 text-txt-secondary">
               <path d="M18 8h-1V6c0-2.76-2.24-5-5-5S7 3.24 7 6v2H6c-1.1 0-2 .9-2 2v10c0 1.1.9 2 2 2h12c1.1 0 2-.9 2-2V10c0-1.1-.9-2-2-2zm-6 9c-1.1 0-2-.9-2-2s.9-2 2-2 2 .9 2 2-.9 2-2 2zm3.1-9H8.9V6c0-1.71 1.39-3.1 3.1-3.1 1.71 0 3.1 1.39 3.1 3.1v2z" />
             </svg>
             <span>