fix: 恢复所有迁移文件以修复校验和错误

恢复了以下迁移文件到原始状态：
- 004_add_redeem_code_notes.sql
- 005_schema_parity.sql
- 006_fix_invalid_subscription_expires_at.sql
- 007_add_user_allowed_groups.sql
- 008_seed_default_group.sql
- 009_fix_usage_logs_cache_columns.sql
- 010_add_usage_logs_aggregated_indexes.sql
- 011_remove_duplicate_unique_indexes.sql
- 012_add_user_subscription_soft_delete.sql
- 013_log_orphan_allowed_groups.sql
- 014_drop_legacy_allowed_groups.sql
- 015_fix_settings_unique_constraint.sql
- 016_soft_delete_partial_unique_indexes.sql
- 018_user_attributes.sql
- 019_migrate_wechat_to_attributes.sql
- 024_add_gemini_tier_id.sql

数据库迁移文件不应在应用后修改，即使只是注释。

backend/migrations/007_add_user_allowed_groups.sql

@@ -1,20 +1,20 @@
--- Add user_allowed_groups join table to replace users.allowed_groups (BIGINT[]).
--- Phase 1: create table + backfill from the legacy array column.
-
-CREATE TABLE IF NOT EXISTS user_allowed_groups (
-    user_id     BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
-    group_id    BIGINT NOT NULL REFERENCES groups(id) ON DELETE CASCADE,
-    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
-    PRIMARY KEY (user_id, group_id)
-);
-
-CREATE INDEX IF NOT EXISTS idx_user_allowed_groups_group_id ON user_allowed_groups(group_id);
-
--- Backfill from the legacy users.allowed_groups array.
-INSERT INTO user_allowed_groups (user_id, group_id)
-SELECT u.id, x.group_id
-FROM users u
-CROSS JOIN LATERAL unnest(u.allowed_groups) AS x(group_id)
-JOIN groups g ON g.id = x.group_id
-WHERE u.allowed_groups IS NOT NULL
-ON CONFLICT DO NOTHING;
+-- Add user_allowed_groups join table to replace users.allowed_groups (BIGINT[]).
+-- Phase 1: create table + backfill from the legacy array column.
+
+CREATE TABLE IF NOT EXISTS user_allowed_groups (
+    user_id     BIGINT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    group_id    BIGINT NOT NULL REFERENCES groups(id) ON DELETE CASCADE,
+    created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    PRIMARY KEY (user_id, group_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_user_allowed_groups_group_id ON user_allowed_groups(group_id);
+
+-- Backfill from the legacy users.allowed_groups array.
+INSERT INTO user_allowed_groups (user_id, group_id)
+SELECT u.id, x.group_id
+FROM users u
+CROSS JOIN LATERAL unnest(u.allowed_groups) AS x(group_id)
+JOIN groups g ON g.id = x.group_id
+WHERE u.allowed_groups IS NOT NULL
+ON CONFLICT DO NOTHING;