Curation v2 step 7: cleanup, prune paths, implementation notes

Dead code and stale v1 comments removed (clippy -W dead_code clean, the
three world.rs warnings fixed), the Brief chapter's TOC title renamed from
"From the Editor", features prune now also sweeps article_assessments and
generate runs the sweep once after publishing, the example config is
tested key-for-key against Config::default(), README commands match
--help, and docs/plans/2026-08-15-implementation-notes.md records the
Anthropic and Voyage facts, the new tables, the budget-day rule and the
lock.

Implemented by a Claude agent from docs/plans/curation-v2-briefs/step7.md.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A1rCLQeKBgnBo3oTgHuTMe

src/curate/profile/mod.rs

@@ -16,7 +16,10 @@ use crate::db::{Db, KV_PROFILE_VERSION, KV_TASTE_PROFILE};
 use crate::types::{Facets, RatedArticle, TasteProfile};
 
 pub const REBUILD_INTERVAL_DAYS: i64 = 7;
-pub const RATINGS_LOOKBACK_DAYS: i64 = 36_500;
+/// The verdict block and the weekly rebuild are bounded by count
+/// (`verdicts_in_prompt`, [`MAX_RATINGS_IN_REBUILD`]), not by age (§8.3, §8.4),
+/// so their `current_ratings` lookback is effectively unbounded.
+const RATINGS_LOOKBACK_DAYS: i64 = 36_500;
 pub const KV_LEARNED_ADJUSTMENTS: &str = "taste_profile_learned";
 const MAX_RATINGS_IN_REBUILD: usize = 200;