Strict lock, transaction handle, single section for a profile switch,
connection generation and blocking alert.
Resolves#408
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The global inTransaction flag let every execute/select bypass the FIFO
lock while a withTransaction callback ran, wherever it came from. The
callback now receives its own handle, which runs directly, refuses
close() and throws once the callback settled; any other call, getDb()
from a callback included, queues behind the transaction.
connectToProfile, initializeNewProfileDb and closeDb each run as one
exclusive section (close the old pool, prepare, load), and every open
or close bumps a connection generation: an operation queued for a
closed connection throws "connection closed by profile switch". An
operation waiting more than 15 s for the lock writes one Journal
warning naming the holder and since when.
findOrCreateSecurity now requires its executor: its getDb() fallback
would deadlock if called from a transaction callback.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
