The directory's lib.rs splits into leaf modules (#356)

The crate root held the wire types, Directory with its refresher and
reloader, and every /v1 handler. It is now the module list and the
re-exports ipx and the directory's main use, so their paths are as
before:

  wire.rs       Listing, FeedPage, SnapshotEntry, ... and MAX_SNAPSHOT
  directory.rs  Directory, Shared, the refresher and the reloader
  api.rs        the router, the token check and the /v1 handlers

Directory's fields and methods are pub(crate) for the handlers beside
it. Its two tests that read those fields went with it, on a scratch
Directory of their own; the API tests stay with the API. Every
definition and doc comment line of the old lib.rs is in exactly one of
the new files.

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

docs/architecture.md

@@ -61,7 +61,10 @@ id, and Caddy's request lines theirs. ipx also serves Prometheus metrics (`[web]
 | `crates/ipx/src/directory.rs` | Asking the directory service, and sharing this server's public feeds with it | — |
 | `crates/ipx/src/metrics.rs` | `/metrics` for Prometheus | — |
 | `crates/ipx/src/signals.rs` | Signals: asks Jev, on each person's TypeSafe key, which of their items fit their Signals | — |
-| `crates/directory/src/lib.rs` | The directory's HTTP API, its token check, the refresher | — |
+| `crates/directory/src/lib.rs` | The directory's modules and what it exports | — |
+| `crates/directory/src/api.rs` | The directory's HTTP API and its token check | — |
+| `crates/directory/src/directory.rs` | `Directory`: its store and tokens, the refresher, the config reloader | — |
+| `crates/directory/src/wire.rs` | What servers and the directory send each other | — |
 | `crates/directory/src/store.rs` | The directory's database: feeds, snapshots, blocked | — |
 | `crates/directory/src/config.rs` | The directory's config file: its tokens and their access | — |
 | `crates/directory/src/otel.rs` | Traces for both Rust services: the exporter, `traceparent` in and out | — |