Review pass: fix bugs, silence clippy, correct docs

Bugs:
- extract: pick the OUTERMOST archive suffix (sfx.first(), not last())
  so x.tar.gz uses the gz->tar path
- gwshop: truncate the error snippet by chars, not bytes (UTF-8 panic)
- sorter: py_stem_split now matches pathlib (0 < i < len-1) so a
  trailing dot is not treated as a suffix
- sorter::apply_plan: a per-file link/copy/mkdir failure is logged and
  skipped instead of aborting the whole apply (never-abort contract)
- orchestrate/state: add State::mark_logged and use it for every
  per-URL record so a state-save error cannot abort a run

Cleanups:
- remove dead is_archive_name and unused SourceInfo.manifest field
- mark kept-but-unused capabilities with allow(dead_code) + rationale
- let-chains / is_ok_and / is_multiple_of / replace([..]) / sort_by_key
  and other idiomatic simplifications across modules
- difflib: SequenceMatcher owns its char vecs (bit-identical parity kept)
- --only now enforces gofile|0807 via value_parser

Docs:
- SORTING.md: drop phantom sorter_plan.jsonl, os.link -> std::fs::hard_link,
  zipfile -> the zip crate
- README: add --since to the dlp synopsis, clarify --subs/--assume-done
- .gitignore: ignore catalogue/sorter/_logs/subscriptions run artifacts

Validation: cargo fmt --check clean, cargo clippy --all-targets 0 warnings,
cargo test 87 passed / 0 failed.

.gitignore

@@ -18,4 +18,12 @@ state.json
 state.json.tmp
 failed_urls.txt
 manifest.jsonl
+catalogue.md
+catalogue.jsonl
+catalogue_moves.jsonl
+sorter_applied.jsonl
+sorter_low_confidence.txt
+subscriptions.json
+*.bak
+_logs/
 *.log