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/database.py

@@ -259,3 +259,119 @@ def test_interleave_by_author_single_author_keeps_order():
     rows = [{"uid": i, "user_uid": "a"} for i in range(4)]
     spread = interleave_by_author(rows)
     assert [r["uid"] for r in spread] == [0, 1, 2, 3]
+
+
+def _relation(actor_uid, target_uid, kind):
+    get_table("user_relations").insert(
+        {
+            "uid": generate_uid(),
+            "user_uid": actor_uid,
+            "target_uid": target_uid,
+            "kind": kind,
+            "created_at": _now_db_helpers(),
+            "deleted_at": None,
+            "deleted_by": None,
+        }
+    )
+
+
+def test_get_user_relations_partitions_both_kinds(local_db):
+    from devplacepy.database import get_user_relations, invalidate_user_relations
+
+    actor = _user_db_helpers()
+    blocked = _user_db_helpers()
+    muted = _user_db_helpers()
+    _relation(actor, blocked, "block")
+    _relation(actor, muted, "mute")
+    invalidate_user_relations(actor)
+
+    relations = get_user_relations(actor)
+    assert relations["block"] == frozenset({blocked})
+    assert relations["mute"] == frozenset({muted})
+
+
+def test_get_user_relations_anonymous_is_empty(local_db):
+    from devplacepy.database import get_user_relations
+
+    relations = get_user_relations(None)
+    assert relations["block"] == frozenset()
+    assert relations["mute"] == frozenset()
+
+
+def test_get_silenced_uids_is_union(local_db):
+    from devplacepy.database import get_silenced_uids, invalidate_user_relations
+
+    actor = _user_db_helpers()
+    blocked = _user_db_helpers()
+    muted = _user_db_helpers()
+    _relation(actor, blocked, "block")
+    _relation(actor, muted, "mute")
+    invalidate_user_relations(actor)
+
+    assert get_silenced_uids(actor) == frozenset({blocked, muted})
+
+
+def test_soft_deleted_relation_is_ignored(local_db):
+    from devplacepy.database import get_blocked_uids, invalidate_user_relations
+
+    actor = _user_db_helpers()
+    target = _user_db_helpers()
+    _relation(actor, target, "block")
+    invalidate_user_relations(actor)
+    assert get_blocked_uids(actor) == frozenset({target})
+
+    row = get_table("user_relations").find_one(user_uid=actor, target_uid=target)
+    get_table("user_relations").update(
+        {"id": row["id"], "deleted_at": _now_db_helpers()}, ["id"]
+    )
+    invalidate_user_relations(actor)
+    assert get_blocked_uids(actor) == frozenset()
+
+
+def test_paginate_excludes_blocked_authors(local_db):
+    from devplacepy.database import paginate, invalidate_user_relations
+
+    viewer = _user_db_helpers()
+    blocked = _user_db_helpers()
+    visible = _user_db_helpers()
+    blocked_post = _post(blocked)
+    visible_post = _post(visible)
+    _relation(viewer, blocked, "block")
+    invalidate_user_relations(viewer)
+
+    rows, _ = paginate(get_table("posts"), viewer_uid=viewer)
+    uids = {r["uid"] for r in rows}
+    assert visible_post in uids
+    assert blocked_post not in uids
+
+
+def test_paginate_without_viewer_keeps_all(local_db):
+    from devplacepy.database import paginate, invalidate_user_relations
+
+    viewer = _user_db_helpers()
+    blocked = _user_db_helpers()
+    blocked_post = _post(blocked)
+    _relation(viewer, blocked, "block")
+    invalidate_user_relations(viewer)
+
+    rows, _ = paginate(get_table("posts"), viewer_uid=None)
+    assert blocked_post in {r["uid"] for r in rows}
+
+
+def test_load_comments_drops_blocked_author(local_db):
+    from devplacepy.database import load_comments, invalidate_user_relations
+
+    viewer = _user_db_helpers()
+    host = _user_db_helpers()
+    blocked = _user_db_helpers()
+    post_uid = _post(host)
+    _comment(blocked, post_uid)
+    _relation(viewer, blocked, "block")
+    invalidate_user_relations(viewer)
+
+    viewer_row = get_table("users").find_one(uid=viewer)
+    comments = load_comments("post", post_uid, viewer_row)
+    assert comments == []
+
+    others = load_comments("post", post_uid, None)
+    assert len(others) == 1