Give every page something to show when it is shared

[DenisDrobyshev]

Only the two landing pages carried Open Graph tags — hand-written, and neither had an image. Checked against the live site, the other fifty-four pages had none at all:

modules/01-claim-baseline-noise/   og:title — ОТСУТСТВУЕТ   og:image — ОТСУТСТВУЕТ
programme/                          og:title — ОТСУТСТВУЕТ   og:image — ОТСУТСТВУЕТ

That is the wrong way round. The shareable unit of a course is a module — «вот модуль про дофамин и TD-обучение» — and the module was the one thing with nothing to show.

How

overrides/main.html emits the tags for every page from its own title and description, inside a social_meta block so the landings replace them instead of appending. Appending would have emitted og:title twice and left the scraper to pick one.

page is None while the theme renders the 404, so every access is guarded. Without that the build dies with 'None' has no attribute 'meta' and mkdocs does not say which template — which is how I found it.

Shadowing main.html is safe here: the theme's own is {% extends "base.html" %} and nothing else. I checked before writing it.

The card

The one the organisation's generator already draws for lemma. Its palette is not a coincidence — #0a0b0e, #f8f9fb and #d8b678 are this site's own ink, paper and gold, so the card and the page a reader lands on are the same design.

twitter:card goes from summary to summary_large_image: a 1280×640 card shown as a thumbnail is a wasted card.

Verified on the built site

page	og:title	count	card
index.html	lemma — дорожная карта…	1	large
en/index.html	lemma — a roadmap…	1	large
modules/01-…/	Модуль 1. Что значит «работает»	1	large
programme/	Программа	1	large
404.html	lemma (falls back, does not crash)	1	large

Exactly one og:title per page — no duplication from the block override. mkdocs build --strict clean, check_modules.py clean.