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/unit/utils.py

@@ -1,6 +1,10 @@
 # retoor <retoor@molodetz.nl>
 
-from devplacepy.database import get_table, get_primary_admin_uid
+from devplacepy.database import (
+    get_table,
+    get_primary_admin_uid,
+    invalidate_admins_cache,
+)
 from devplacepy.utils import (
     award_badge,
     award_xp,
@@ -168,6 +172,7 @@ def _seed_user_at(role, created_at):
             "created_at": created_at.isoformat(),
         }
     )
+    invalidate_admins_cache()
     return get_table("users").find_one(uid=uid)
 
 
@@ -175,12 +180,14 @@ def _demote_existing_admins():
     existing = [r["uid"] for r in get_table("users").find(role="Admin")]
     for uid in existing:
         get_table("users").update({"uid": uid, "role": "Member"}, ["uid"])
+    invalidate_admins_cache()
     return existing
 
 
 def _restore_admins(uids):
     for uid in uids:
         get_table("users").update({"uid": uid, "role": "Admin"}, ["uid"])
+    invalidate_admins_cache()
 
 
 def _purge(*rows):
@@ -219,6 +226,7 @@ def test_primary_admin_reassigns_when_founder_demoted(local_db):
         get_table("users").update(
             {"uid": admin_first["uid"], "role": "Member"}, ["uid"]
         )
+        invalidate_admins_cache()
         assert get_primary_admin_uid() == admin_second["uid"]
         assert (
             is_primary_admin(get_table("users").find_one(uid=admin_second["uid"]))