site: cut the template's own labels out of the pages

Point 7 of the page-wording review. The pages no longer show their data
structure as headings, and they no longer explain their own conventions.

- Level 1 is one screen: claim, status badge, three figures, the technology
  row, and one sentence carrying one link. Measured in headless Chrome at
  1440x900: 1404-1845 px tall before, exactly 900 px (no scroll) after, on
  all six area pages.
- DocPage: no kicker line, no visible level label, no "Evidence for this
  page" heading or instruction note, no "Drill-downs" list, no
  "Status <word> - sentence" footer. The artefact table starts at level 2,
  under the heading "Artefacts"; the history timeline is level 2 only.
- Landing page: "Start here" link text gone, "How to read this site" panel
  gone, the footer's status-label explainer gone.
- Content, presentation only, no claim softened: the leading H1 that
  duplicated the page title removed from all 41 documents; level 1 bodies
  reduced to the constraint as ordinary prose plus the way in;
  "**Status: ...**" prefixes removed from the artefact stubs; "## Drill-downs"
  and "## Period and confidence" removed from the level 2 pages, with the
  cross-area links moved into the prose.
- The six level 1 claims are now sentences with a subject, and use commas
  instead of middots. Same facts, no new ones.

Not in this commit: the 35 level 2 and 3 claims still use the compact CV
style. That is a voice decision for Sam, not a wording tidy-up.

make validate: 41 documents, 0 violations. go test ./...: pass.

(cherry picked from commit 03009f80fc7815ad7719412e125df9297a6e653f)

content/history/history-engagements.md

@@ -14,8 +14,6 @@ last_verified: 2026-10-26
 tags: [history, agencies, brands, exhibits]
 ---
 
-# Fifteen years of delivery for agencies and their clients
-
 **Capability statement.** Range under deadline. The work in this period ran from car classifieds and online betting to a bank's pitch piece, a broadcaster's on-demand banners and a publisher's education platform — usually with a date attached that could not move.
 
 ## The eras, briefly
@@ -52,12 +50,4 @@ The point of the exhibit set is that the tooling changed repeatedly and the deli
 - **No client has been named beyond a brand.** Brands are named because they were public campaigns. Individuals, internal contacts and unpublished commercial detail are excluded.
 - **The exhibits are excerpts.** Around forty lines each, chosen to show judgement — structure, error handling, an exit plan — not to demonstrate volume.
 
-## Drill-downs
-
-- [The client wall](l3/history-client-wall.md) — level 3
-- [Six code exhibits across five eras](l3/history-code-exhibits.md) — level 3
-- [Products — the commercial era that followed](../products/products-business.md) — level 2
-
-## Period and confidence
-
-`period: 1999–2014`. Confidence is `historic`: this is work that is finished, and it is presented in the past tense throughout.
+This work is finished, and it is presented in the past tense throughout.