[rumblefrog]

Summary

Follow-up to #1475 (full data export). Two paired changes:

• New Conventions block in AGENTS.md — User-facing text style (panel UI + docs). Three rules: no emdash (—), terse, don't over-explain. Scoped to the surfaces operators read: web/themes/default/**/*.tpl, \Sbpp\View\Toast::emit titles + bodies, echo output from page handlers, and every docs/src/content/docs/**/*.{md,mdx} page. Explicit carve-out for contributor docs (AGENTS.md, ARCHITECTURE.md, etc.), PHP/JS/Smarty code comments, audit-log entries, and test fixtures. Paired Anti-patterns entries pin the rule.
• Wording fixes on the surfaces feat(export): full data export — ZIP download + S3 presigned upload #1475 added:
  • web/themes/default/page_admin_export.tpl — page intro, bundle summary, cap-exceeded body, ZIP and S3 form descriptions.
  • web/pages/admin.export.php — sbpp_admin_export_describe_error() error-code translations.
  • docs/src/content/docs/configuring/data-export.mdx — every section rewritten for terseness; emdashes removed.

The rule covers the user-visible surface only. AGENTS.md and code comments still use emdashes freely; both halves of the carve-out are documented.

Test plan

• ./sbpp.sh phpstan — clean.
• ./sbpp.sh ts-check — clean (no JS touched).
• ./sbpp.sh test --filter='ExportBundleWriterTest|EntityExporterTest|ManifestBuilderTest|AdminExport|S3PresignedUploaderTest' — 44 tests, 603 assertions, green.
• No test pinned the rewritten strings (verified by rg against web/tests/).
• rg "—" over docs/src/content/docs/configuring/data-export.mdx, the rendered surface of web/themes/default/page_admin_export.tpl, and the user-facing strings in web/pages/admin.export.php returns zero matches.
• Manual smoke: render ?p=admin&c=export as owner, trigger an error redirect via ?result=error&code=presign_invalid_scheme, confirm the toast body reads as expected.

Notes

• Tag mapping unchanged. No DB migration. No new permission flag.
• The merge-commit subject of feat(export): full data export — ZIP download + S3 presigned upload #1475 itself carries an emdash; the rule applies prospectively to user-facing strings, not to historical commit history.