fix: comment score regression

PR #547 introduced a UI bug where the comment score tooltip would
show the wrong values (and in fact, the displayed score was also
wrong, though this was not originally noticed).

Specifically, a comment with e.g. +4 | -1 would display in the tooltip
as being +4 | -4 and display a score of 4. The desired behavior would
be +4 | -1 and score of 3. Precisely, the upvote value was displayed
for each of upvotes, downvotes, and net score.

Root cause was the `@lazy` decorator at:
`files.classes.comment._score_context_str(⋅)`

`@lazy` is very dumb. I don't entirely know why we don't just use
`functools.cache`, but we use `@lazy` everywhere. It is entirely
ignorant of the parameters to a function--not a substitute for
memoization.

comments.html contains the following snippet:

    {%- set ups = c.upvotes_str(render_ctx) -%}
    {%- set score = c.score_str(render_ctx) -%}
    {%- set downs = c.downvotes_str(render_ctx) -%}

Each of those three functions internally calls to `_score_context_str`
but with different arguments. The first call to upvotes gets cached by
`@lazy` and the two subsequent calls get the upvotes string, rather than
what they wanted. It's a cheap enough operation that it's not really
worth memoizing, so we just remove the decorator.

files/classes/comment.py

@@ -91,13 +91,12 @@ class Comment(Base):
 		comment_age_hours = comment_age_seconds / (60*60)
 		return comment_age_hours < app.config['SCORE_HIDING_TIME_HOURS']
 	
-	@lazy
 	def _score_context_str(self, score_type:Literal['score', 'upvotes', 'downvotes'], 
 			context:CommentRenderContext) -> str:
 		if self.is_message: return '' # don't show scores for messages
 		if context == 'volunteer': return '' # volunteer: hide scores
 		if self.should_hide_score: return '' # hide scores for new comments
-		
+
 		if score_type == 'upvotes': return str(self.upvotes)
 		if score_type == 'score': return str(self.score)
 		if score_type == 'downvotes': return str(self.downvotes)