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/routers/docs/pages.py

@@ -63,6 +63,18 @@ DOCS_PAGES = [
         "kind": "prose",
         "section": SECTION_GENERAL,
     },
+    {
+        "slug": "block-and-mute",
+        "title": "Block and mute",
+        "kind": "prose",
+        "section": SECTION_GENERAL,
+    },
+    {
+        "slug": "emoji-shortcodes",
+        "title": "Emoji shortcodes",
+        "kind": "prose",
+        "section": SECTION_GENERAL,
+    },
     {
         "slug": "devii",
         "title": "Devii Assistant",