fix: consistent avatar gradient colors across all 17 call sites

Avatar fallback gradients were hashed by display name alone when no
user prop was passed, causing the same person to appear in different
colors across messages, replies, member lists, voice panels, etc.

Added userId prop to Avatar and wired it through all 17 call sites
so the gradient always hashes by user ID.

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

@@ -122,7 +122,7 @@ export function AddDmMemberModal() {
               disabled={isAdding}
               className="w-full flex items-center gap-3 px-3 py-2 rounded-[4px] hover:bg-interactive-hover transition-colors text-left disabled:opacity-50"
             >
-              <Avatar src={user.avatar} name={user.displayName ?? user.username} size={36} status={user.status as any} />
+              <Avatar src={user.avatar} name={user.displayName ?? user.username} size={36} status={user.status as any} userId={user.id} />
               <div className="flex-1 min-w-0">
                 <div className="text-[14px] font-medium text-txt-primary truncate">
                   {user.displayName ?? user.username}