docs: add block/mute user relations, emoji-sync CLI, and uid indexes

- Add `/block`, `/mute` endpoints with block/unblock and mute/unmute functionality in `routers/relations.py`, hiding blocked users' content everywhere except their own profile while muting only suppresses notifications
- Introduce `devplace emoji-sync` CLI command to regenerate `static/js/emoji-shortcodes.js` from the emoji library, documented in `CLAUDE.md` and wired in `cli.py`
- Create `get_blocked_uids()` database helper and apply it in `content.py` `load_detail()` to filter blocked users' posts from detail views
- Implement `_uid_index()` and `_drop_index()` helpers in `database.py` for unique uid indexes across tables, with `user_relations` added to `SOFT_DELETE_TABLES`
- Document new routes in `AGENTS.md` and `README.md`, including emoji shortcodes rendering behavior distinct from the emoji picker

devplacepy/templates/_comment.html

@@ -1,14 +1,14 @@
 {% macro render_comment(item, depth=0) %}
 <div class="comment" style="--comment-depth: {{ depth }};" data-depth="{{ depth }}">
-    <div class="comment-votes">
+    <div class="comment-votes" role="group" aria-label="Comment votes">
         <form method="POST" action="/votes/comment/{{ item.comment['uid'] }}">
             <input type="hidden" name="value" value="1">
-            <button type="submit" class="comment-vote-btn vote-up{% if item.my_vote == 1 %} voted{% endif %}" aria-label="Upvote" title="Upvote"{{ guest_disabled(user) }}>+</button>
+            <button type="submit" class="comment-vote-btn vote-up{% if item.my_vote == 1 %} voted{% endif %}" aria-label="Upvote" title="Upvote" aria-pressed="{% if item.my_vote == 1 %}true{% else %}false{% endif %}"{{ guest_disabled(user) }}>+</button>
         </form>
         <span class="comment-vote-count" data-vote-count="{{ item.comment['uid'] }}">{{ item.votes.up - item.votes.down }}</span>
         <form method="POST" action="/votes/comment/{{ item.comment['uid'] }}">
             <input type="hidden" name="value" value="-1">
-            <button type="submit" class="comment-vote-btn vote-down{% if item.my_vote == -1 %} voted{% endif %}" aria-label="Downvote" title="Downvote"{{ guest_disabled(user) }}>-</button>
+            <button type="submit" class="comment-vote-btn vote-down{% if item.my_vote == -1 %} voted{% endif %}" aria-label="Downvote" title="Downvote" aria-pressed="{% if item.my_vote == -1 %}true{% else %}false{% endif %}"{{ guest_disabled(user) }}>-</button>
         </form>
     </div>