P2-ops: migration alignment, deploy test list, monitor alerts/single-host, backup/rollback closure, Caddy template

- migrations: MIGRATION_TABLES now equals POSTGRES_SCHEMA tables
  (uploads, task_attachments, task_followups, environments added);
  SEQUENCE_TABLES matches IDENTITY tables; task_followups
  sender_task_id column ensured before insert; UNMIGRATED_TABLES
  and migration_coverage() report tables with no PG schema instead
  of silently skipping them; CLI prints the coverage report.
- deploy: DEFAULT_TEST_SUITES gains deploy/tests (discover -s only,
  never package path); regression tests pin the default list.
- monitor: MONITOR_SINGLE_HOST=1 makes the server check single-host;
  default stays dual to avoid silent downgrade; server_mode is in
  the JSON. Optional fail-only alert outlet (webhook or mail,
  default off, alert body is pass/fail JSON only, no secrets).
- backup/rollback: README and restore-drill document what is
  recoverable (DB, code) vs not (worktrees, traces, uploads, host
  configs); rollback.sh shares the server-unit list and dual-port
  health success standard with host_deploy.sh (sync test guards it).
- public entry: Caddyfile uses native {$DOMAIN}/{$ACME_EMAIL}
  variables plus a caddy.service template; README documents the
  steps and the current BT-nginx production status.

cloud/migrate_sqlite_to_postgres.py

@@ -15,7 +15,10 @@
 import argparse
 import sys
 
-from cloud.migrations import migrate_sqlite_to_postgres
+from cloud.migrations import (
+    migrate_sqlite_to_postgres,
+    migration_coverage,
+)
 
 
 def main(argv=None):
@@ -30,6 +33,17 @@ def main(argv=None):
         print("%s: %d" % (table, count))
         total += count
     print("total inserted: %d" % total)
+    # 覆盖报告：只含表名，不含行内容与任何密钥。missing 非空
+    # 即清单与 schema 对齐回归；unmigrated 是目标库无此表、
+    # 本迁移无法迁移的表，须另行处理，不能读成“已迁完”。
+    coverage = migration_coverage()
+    if coverage["missing_from_migration"]:
+        print("WARNING missing_from_migration: %s"
+              % ", ".join(coverage["missing_from_migration"]))
+    print("unmigrated (no PG schema, NOT migrated): %s"
+          % ", ".join(coverage["unmigrated_no_pg_schema"]))
+    print("skipped by design: %s"
+          % ", ".join(coverage["skipped_by_design"]))
     return 0