Three durable ledgers used `with _connect() as conn:` where the sqlite3
connection context manager commits/rolls back but never closes, leaking the
db/-wal/-shm file descriptors on every call. On a long-running gateway this
exhausts RLIMIT_NOFILE and fails unrelated components with
`[Errno 24] Too many open files`. Same bug class as the cron execution ledger
(#69567 / PR #69594), which the connection helpers here are modeled on.
Fix: route every ledger operation through a `_transaction()` context manager
that guarantees `conn.close()` on exit. `_connect()` keeps its
schema-on-connect contract (several tests call it directly) and now self-closes
if schema init fails.
Adds per-module regression tests asserting every opened connection is closed,
including the no-op-update and exception-mid-transaction paths.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Dhruv Raajeev