Track user TZ, show timestamps on pages
Set single connection for sqlite pool.
With multiple connections, write contention can cause errors (e.g.
[SQLITE_BUSY](https://www.sqlite.org/rescode.html#busy)). A single connection
obviously constrains throughput, but should be significantly more durable
without needing a bunch of retry logic shotgunned throughout.
The real fix for this is to use a real database.
Collect and log individual feed update errors
Bulk operations and some restyling.
Still to be done:
* select-all
* UI to review/undelete deleted entries
indicate version in web UI