Fix world briefing & add LLM enrichment, colophon fix, x4 cover fix

- World Briefing now starts with yesterday, preserves complete nested
event hierarchies and Wikipedia links, fetches deduplicated article
leads concurrently, and adds stable-ID summaries plus a daily overview.
- Enrichment runs after normal editorial work and degrades safely with
report warnings.
- Colophon facts now use X4-safe block paragraphs.
- Standard cover remains 1200×1600 RGB PNG.
- X4 cover is a 480×800 baseline RGB JPEG with consistent XHTML and OPF
declarations.
- Added CrossInk cache-clearing guidance to README.md.
- Worked around an epub-builder duplicate XML-ID defect discovered by
validation.

src/lib.rs

@@ -8,8 +8,8 @@
 //!
 //! ```text
 //! Miniflux ingest → dedupe → extraction → persist → social enrichment
-//!   → pre-filter → LLM scoring → selection → comments → world briefing
-//!   → editorial → EPUB build (standard + X4) → XTC → publish → report
+//!   → pre-filter → LLM scoring → selection → comments → editorial
+//!   → world briefing → EPUB build (standard + X4) → XTC → publish → report
 //! ```
 
 pub mod auth;