Cargo workspace: crates/ipx and a shared crates/feed (#202)

The first step of the split (#207). The daemon moves to crates/ipx unchanged;
feed.rs becomes crates/feed (ipx-feed), which the directory service (#204)
will share for its metadata refresher and its privacy check.

To stand alone, fetch takes the feed's address and its credentials instead
of ipx's config::Feed (config::Feed::auth gives them), collect_outlines
moves in with the OPML parsing, and the address half of looks_private is
feed::url_looks_private. ipx imports the crate as `feed` at its root, so
every crate::feed path is unchanged. The version is the workspace's, in the
root Cargo.toml.

Checked: cargo test on Postgres (118 + 29), tsc, page smoke, native bridge,
contrast and Playwright (72) pass; the image built from the new Dockerfile
is deployed and healthy.

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

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add a feed no longer asks for a folder; a feed's folder is its title (#201).
 - `docker-compose.yml` is a sample to start from, ipx alone on SQLite with its folders beside the file, instead of a copy of the author's server (#208).
+- The source is a Cargo workspace: the daemon in `crates/ipx`, feed fetching and parsing in `crates/feed`. `cargo build --release` still makes `target/release/ipx` (#202).
 
 ## [0.12.0] - 2026-10-11