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>

docs/architecture.md

@@ -27,7 +27,14 @@ id, and Caddy's request lines theirs. ipx also serves Prometheus metrics (`[web]
 
 | File | Responsibility | What it replaced in the Python |
 |---|---|---|
-| `crates/ipx/src/main.rs` | CLI, dispatch, scan loop, download policy | `iPXAgent.py` |
+| `crates/ipx/src/main.rs` | The module list and `main`: reads the command line and hands it on | `iPXAgent.py` |
+| `crates/ipx/src/cli.rs` | The commands, and what each does when no daemon takes it | `iPXAgent.py` |
+| `crates/ipx/src/ctx.rs` | `Ctx`, what every command shares: configuration, database, clients | — |
+| `crates/ipx/src/daemon.rs` | The daemon: worker loop, web server, shutdown, `status` | `iPXAgent.py` |
+| `crates/ipx/src/scan.rs` | When a feed is due, reading it, download policy, downloads and torrents | `iPXAgent.py` |
+| `crates/ipx/src/catalogue.rs` | Adding, removing and leaving feeds; subscriptions; retiring a list's feeds | — |
+| `crates/ipx/src/lists.rs` | OPML import, and keeping an OPML's or a Patreon creator's feeds in step | — |
+| `crates/ipx/src/logging.rs` | Logging setup, and JSON lines carrying their trace | — |
 | `crates/ipx/src/config.rs` | TOML load/save, `General`/`Feed`/`Web`, intervals, slugs | `iPXSettings.py`, `feeds.plist` |
 | `crates/ipx/src/db.rs` | Every query, through SeaORM; creates missing tables | `.ipxd` plists, `history.dat`, `qmcache.dat` |
 | `crates/ipx/src/entity.rs` | The tables, as SeaORM entities: the schema | — |