ipx's main.rs splits into leaf modules (#356)

main.rs held 3,200 lines: the command line, the shared context, the
daemon, scans, downloads, the catalogue and OPML, and their tests. The
style guide keeps a root module to declarations and a little glue, the
code in leaf modules named for what they hold:

  cli.rs        the commands, run and user_cmd, ago and duration
  ctx.rs        Ctx and CfgEdit, and Ctx::new, which main() built inline
  daemon.rs     the daemon's loop, web server, shutdown, status, reload
  scan.rs       due_at/due_after, scan_one, policy, downloads, torrents
  catalogue.rs  add/rm/leave/remove_user, subscriptions, retiring lists
  lists.rs      OPML import and syncing an OPML's or a creator's feeds
                (not opml.rs, which would shadow the opml crate)
  logging.rs    logging::init and the JSON lines with their trace
  test_util.rs  the context, feeds and feed server tests share

first_password moves to auth.rs and reap to retention.rs. Each test went
with what it tests; all 151 still run. main.rs is the module list and a
main() that hands the command on, 113 lines.

Moved verbatim, then made pub(crate) where a sibling calls it, with
calls across modules written module::function as the guide asks.
Everything the old main.rs defined is defined once in the new files.

With Ctx no longer a pub type at the crate root, Db's pub methods stop
counting as public API, and the compiler sees what nothing outside tests
calls: entries_in, count_in, unread_count and feed_description are now
#[cfg(test)], and media_feeds, called by nothing, is gone.

ipx depends on opentelemetry_sdk directly now (it was already in the
lock through ipx-directory), for logging::init's signature.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Cargo.lock

@@ -1875,6 +1875,7 @@ dependencies = [
  "jsonwebtoken",
  "librqbit",
  "opentelemetry",
+ "opentelemetry_sdk",
  "opml",
  "percent-encoding",
  "reqwest",