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

tests/e2e/feed.py

@@ -503,10 +503,9 @@ def test_feed_tab_switching(alice):
 def test_feed_topic_filter_sidebar(alice):
     page, user = alice
     page.goto(f"{BASE_URL}/feed", wait_until="domcontentloaded")
-    page.locator(".sidebar-more .sidebar-more-toggle").click()
     topics = ["Devlog", "Showcase", "Question", "Rant", "Fun"]
     for topic in topics:
-        link = page.locator(f"a:has-text('{topic}')").first
+        link = page.locator(f".sidebar-nav a:has-text('{topic}')").first
         assert link.is_visible()
 
 
@@ -689,8 +688,7 @@ def test_feed_guest_reply_disabled(page, app_server):
 def test_feed_signals_topic(alice):
     page, _ = alice
     page.goto(f"{BASE_URL}/feed", wait_until="domcontentloaded")
-    page.locator(".sidebar-more .sidebar-more-toggle").click()
-    signals_link = page.locator("a:has-text('Signals')")
+    signals_link = page.locator(".sidebar-nav a:has-text('Signals')")
     assert signals_link.is_visible()