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.toml

@@ -6,6 +6,7 @@ edition = "2024"
 [dependencies]
 anyhow = "1.0.104"
 atom_syndication = "0.12.10"
+chrono = { version = "0.4.45", default-features = false, features = ["std", "clock"] }
 clap = { version = "4.6.6", features = ["derive"] }
 dirs = "7.0.0"
 infer = "0.22.0"