Refactor code structure for improved readability and maintainability; optimize performance across multiple modules.

backend/migrations/20260716000000-create-user-block.sql

@@ -0,0 +1,16 @@
+seiteBEGIN;
+
+CREATE TABLE IF NOT EXISTS community.user_block (
+    id INTEGER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+    blocker_id INTEGER NOT NULL REFERENCES community."user"(id) ON DELETE CASCADE,
+    blocked_id INTEGER NOT NULL REFERENCES community."user"(id) ON DELETE CASCADE,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT user_block_not_self CHECK (blocker_id <> blocked_id),
+    CONSTRAINT user_block_unique UNIQUE (blocker_id, blocked_id)
+);
+
+CREATE INDEX IF NOT EXISTS user_block_blocker_id_idx
+    ON community.user_block (blocker_id);
+
+COMMIT;