feat: import Chinese-localized Buzz source snapshot

Signed-off-by: cls_宁波本机 <908705107@qq.com>

migrations/0020_join_policy_acceptances.sql

@@ -0,0 +1,12 @@
+-- Durable evidence of the policy version accepted when an invite claim grants
+-- relay membership. Rows are scoped to the same community and member identity
+-- as relay_members and are deleted with that membership.
+CREATE TABLE join_policy_acceptances (
+    community_id UUID NOT NULL,
+    pubkey TEXT NOT NULL,
+    policy_version TEXT NOT NULL CHECK (length(policy_version) = 64),
+    accepted_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (community_id, pubkey, policy_version),
+    FOREIGN KEY (community_id, pubkey)
+        REFERENCES relay_members (community_id, pubkey) ON DELETE CASCADE
+);