autocomplete: fix usernames not being highlighted in @mentions.

Fix usernames not being highlighted when completing @mentions.

This also changes it so the autocomplete results don't include the '@'
in front of the name.

Minor breaking change to the /autocomplete.json API. Autocomplete
results for mentions now have the type `mention` instead of `user`.

app/components/autocomplete_component.rb

@@ -12,7 +12,7 @@ class AutocompleteComponent < ApplicationComponent
 
   def link_to_result(result, &block)
     case result.type
-    when "user"
+    when "user", "mention"
       link_to user_path(result.id), class: "user-#{result.level}", "@click.prevent": "", &block
     when "pool"
       link_to pool_path(result.id), class: "pool-category-#{result.category}", "@click.prevent": "", &block
@@ -34,6 +34,8 @@ class AutocompleteComponent < ApplicationComponent
   def highlight_result(result)
     if result.type == "tag-word"
       highlight_matching_words(result.value, query)
+    elsif result.type == "mention"
+      highlight_wildcard_match(result.label, query + "*")
     elsif metatag.present? && metatag.value.include?("*")
       highlight_wildcard_match(result.label, metatag.value)
     elsif metatag.present? && metatag.name.in?(%w[pool favgroup])

app/logical/autocomplete_service.rb

@@ -362,7 +362,7 @@ class AutocompleteService
   # @return [Array<Hash>] the autocomplete results
   def autocomplete_mention(string)
     autocomplete_user(string).map do |result|
-      { **result, value: "@" + result[:value] }
+      { **result, type: "mention", value: "@" + result[:value] }
     end
   end