feat(core): word-count breakdown in header — article vs chrome split

Current Word count: N is a single number conflating article body
and surrounding chrome (nav, ads, footer). Callers couldn't tell
from the header alone whether to drill or move on.

New: Word count: N (article: M, chrome: K) in -f llm/text output.
For -f json: adds word_count_article and word_count_chrome
fields alongside the existing word_count.

M (article body) is sourced from JSON-LD articleBody when M4's
parser found one (NewsArticle or Review.reviewBody); otherwise
computed by llm::body_word_count (the M2-style heuristic — words
outside markdown link patterns, the same body::process_body output
hub_detect uses).

--mode summary / toc / sections fall back to the simple Word count: N
form (the modes don't extract body content; the breakdown would be
meaningless). Suppression piggybacks on the existing include_status
toggle in build_metadata_header_with_opts.

9 new tests in webclaw-core (4 in lib.rs::tests for the population
logic; 5 in llm/metadata.rs::m12_tests for the header formatter).
Workspace 701 -> 710.

crates/webclaw-fetch/src/client.rs

@@ -899,6 +899,10 @@ fn pdf_to_extraction_result(
             image: None,
             favicon: None,
             word_count,
+            // M12: PDF text is body content end-to-end (no nav/chrome
+            // wrapper extracted around it). Treat all words as article.
+            word_count_article: word_count,
+            word_count_chrome: 0,
             http_status: None,
         },
         content: webclaw_core::Content {

crates/webclaw-fetch/src/document.rs

@@ -110,6 +110,10 @@ pub fn extract_document(
             image: None,
             favicon: None,
             word_count,
+            // M12: document extractors (DOCX, CSV, etc.) emit body content
+            // only; no chrome envelope. All words are article.
+            word_count_article: word_count,
+            word_count_chrome: 0,
             http_status: None,
         },
         content: webclaw_core::Content {

crates/webclaw-fetch/src/linkedin.rs

@@ -216,6 +216,11 @@ pub fn extract_linkedin_post(html: &str, url: &str) -> Option<ExtractionResult>
             image: None,
             favicon: None,
             word_count,
+            // M12: LinkedIn post payload IS the article body; comments
+            // and reactions are appended below but treated as article
+            // for this extractor (no separate chrome envelope).
+            word_count_article: word_count,
+            word_count_chrome: 0,
             http_status: None,
         },
         content: Content {

crates/webclaw-fetch/src/reddit.rs

@@ -92,6 +92,10 @@ pub fn parse_reddit_json(json_bytes: &[u8], url: &str) -> Result<ExtractionResul
             image: None,
             favicon: None,
             word_count,
+            // M12: Reddit JSON path emits post body + comments; no chrome
+            // wrapper. All words are article-side content.
+            word_count_article: word_count,
+            word_count_chrome: 0,
             http_status: None,
         },
         content: Content {