Topic tag filters: one per line instead of commas

A few minor interface improvements for topic tag filters - mostly just
changing to the settings page defining them in a textarea, with one per
line. Previously this was just a text input with the tags
comma-separated, which got unwieldy very quickly.

tildes/tildes/templates/settings_filters.jinja2

@@ -21,8 +21,14 @@
       username=request.user.username,
     ) }}"
 >
-  <label class="form-label" for="tags">Tags (comma-separated):</label>
-  <input type="text" class="form-input" name="tags" id="tags" value="{{ request.user.filtered_topic_tags|join(', ') }}">
+  <label class="form-label" for="tags">Filtered tags (one per line):</label>
+  <textarea
+    class="form-input"
+    name="tags"
+    id="tags"
+    data-js-ctrl-enter-submit-form
+    data-js-auto-focus
+  >{{ request.user.filtered_topic_tags|join("\n") }}</textarea>
   <div class="form-buttons">
     <button class="btn btn-primary" type="submit">Save filtered tags</button>
   </div>

tildes/tildes/views/api/web/user.py

@@ -330,11 +330,11 @@ def put_default_listing_options(
 @use_kwargs({"tags": String()})
 def put_filtered_topic_tags(request: Request, tags: str) -> dict:
     """Update a user's filtered topic tags list."""
-    if not tags:
+    if not tags or tags.isspace():
         request.user.filtered_topic_tags = []
         return IC_NOOP
 
-    split_tags = tags.split(",")
+    split_tags = tags.replace("\r", "").split("\n")
 
     try:
         schema = TopicSchema(only=("tags",))