Unwrap Scour's /r/rss/ redirector when canonicalizing URLs

Scour interest feeds link every entry through
https://scour.ing/r/rss/<percent-encoded article URL>, so the wrapper
became the article's canonical URL: the same post arriving via Hacker
News and Scour never merged, and the publication fallback showed
"scour.ing" instead of the site's own domain. Resolve the wrapper like
the Google News redirector. `publication_label` re-canonicalizes the
stored URL so the 477 articles saved with the wrapper show the real
domain too.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VXYGBPoHZSDSfE5WcJ9bvj

Cargo.toml

@@ -23,6 +23,7 @@ jiff = { version = "0.2.35", features = ["serde"] }
 lettre = { version = "0.11", default-features = false, features = ["builder", "smtp-transport", "tokio1", "tokio1-rustls-tls", "hostname"] }
 libc = "0.2.189"
 password-auth = "1.0.0"
+percent-encoding = "2.3.2"
 rand = "0.10.2"
 reqwest = { version = "0.13.4", default-features = false, features = [
     "rustls",