Resolve share URLs from the instance host and ship 1200×630 Open Graph images.

Staging no longer advertises production canonicals, and Slack/social previews get a default hero card with template and article overrides.

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitignore

@@ -50,6 +50,11 @@ npm-cache/
 # Marketing book cover (raster; see docs/guides/static-assets.md)
 !public/assets/marketing/community-rules-cover.png
 
+# Open Graph 1200×630 share images (`npm run generate:og-images`)
+!public/assets/marketing/og-image.png
+!public/assets/marketing/og-image-templates.png
+!public/content/blog/*-og.png
+
 # Visual regression snapshots (allow these)
 !tests/e2e/visual-regression.spec.ts-snapshots/
 !tests/e2e/visual-regression.spec.ts-snapshots/*.png