Step 2: TOML config and SQLite state

config.rs replaces iPXSettings.py and feeds.plist; db.rs replaces the
per-feed .ipxd plists, history.dat and qmcache.dat. enclosures.url is
UNIQUE, which is the dedupe key the old pickle history provided.

ipx list is the first working subcommand.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RPyeapneuXrCdojsaiXGbe

Cargo.lock

@@ -1500,6 +1500,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "atom_syndication",
+ "chrono",
  "clap",
  "dirs",
  "infer",