Use "Link" as the default content type for links

Previously a topic with an unknown content type would display "Article".
This switches to "Link" which will have some different idiosyncracies,
but should be a little more correct in general.

tildes/tildes/models/topic/topic.py

@@ -408,15 +408,16 @@ class Topic(DatabaseModel):
 
         return False
 
-    @property
-    def content_type(self) -> TopicContentType:
+    @property  # noqa
+    def content_type(self) -> Optional[TopicContentType]:
         """Return the content's type based on the topic's attributes."""
         if self.is_text_type:
             if self.has_tag("ask"):
                 return TopicContentType.ASK
 
             return TopicContentType.TEXT
-        else:
+
+        if self.is_link_type:
             parsed_url = urlparse(self.link)  # type: ignore
             url_path = PurePosixPath(parsed_url.path)
 
@@ -435,7 +436,12 @@ class Topic(DatabaseModel):
             except IndexError:
                 pass
 
-            return TopicContentType.ARTICLE
+            # consider it an article if we picked up a word count of at least 200
+            word_count = self.get_content_metadata("word_count")
+            if word_count and word_count >= 200:
+                return TopicContentType.ARTICLE
+
+        return None
 
     def get_content_metadata(self, key: str) -> Any:
         """Get a piece of content metadata "safely".

tildes/tildes/templates/macros/topics.jinja2

@@ -46,7 +46,7 @@
         </ul>
       {% endif %}
 
-      <span class="topic-content-type">{{ topic.content_type.display_name }}</span>
+      <span class="topic-content-type">{{ topic.content_type.display_name if topic.content_type else "Link" }}</span>
 
       {% if topic.content_metadata_for_display %}
         <span class="topic-content-metadata">: {{ topic.content_metadata_for_display }}</span>