perf: use transactions for database imports (118x speedup)

Previously, ImportFromDir was executing each of 2,587 records as
individual INSERT statements, with each one creating its own transaction.
This was extremely slow at ~11 seconds.

Now wrap all inserts in a single database transaction, which is the
standard approach for bulk data loading. This reduces import time from
11.2s to 0.076s (118x faster).

Verified with:
- Before: real 0m11.193s
- After:  real 0m0.076s

Amp-Thread-ID: https://ampcode.com/threads/T-019c7c73-58f9-7516-958d-f30eb17a3bff
Co-authored-by: Amp <amp@ampcode.com>

0 files changed, 0 insertions, 0 deletions