docs: fix drifted facts in the org profile, site, and contributor docs

[lesnik512]

Summary

A review of the org repo found facts that drifted from their sources. Each was checked against the source before changing it.

Changes

• Delete brand/STORY.md and brand/story-assets/. A grep of the whole repo (mkdocs.yml, tests, brand build scripts, READMEs) found no references outside STORY.md itself. brand/README.md did not link to it.
• profile/README.md: the httpware row said "Python HTTP client framework with sync & async clients and built-in resilience". httpware/pyproject.toml says "Typed, resilient HTTP clients for Python, sync and async" (MD1). Every other profile row already matched its pyproject.
• docs/index.md catalog: every row now uses its repo's pyproject description. Rows that had drifted: both templates (the litestar one was missing "with DI"), modern-di, all modern-di-* integrations (modern-di-pytest called itself a plain integration), that-depends, lite-bootstrap, httpware, faststream-redis-timers, faststream-concurrent-aiokafka, faststream-outbox, db-retry, eof-fixer, and semvertag. The list separator is now : instead of an em dash. The httpware row now uses the pyproject string, which supersedes the "add circuit breaker" fix. The stack section at docs/index.md:77 already lists retry, bulkhead, and circuit breaker.
• Add chat-app, a public repo, to the Project templates table and the site catalog. It uses chat-app/pyproject.toml's description: "Reference chat application for the modern-python organisation". tests/test_profile.py requires every profile row to have a project mark, so it also gets a MANIFEST entry in brand/build/projects.py. Like the templates, it reuses the org chevron because it is not a published library. Its rendered assets are in brand/projects/chat-app/, and it is added to scripts/check_site_content.sh.
• CONTRIBUTING.md: every sibling repo has a justfile, so the "where a justfile exists" clause is gone. The suggested check uv run ruff check . applies fixes because the canonical ruff config sets fix = true and unsafe-fixes = true, so the step now points to just lint-ci, which is read-only, and just lint, which fixes. The templates and chat-app have no lint-ci recipe, and the text says so. Of the sibling justfiles, only that-depends/justfile:11-12,17-18 runs mypy and pyrefly.
• brand/README.md: the icon is a chevron between the two snakes (brand/build/geometry.py:6-17, _icon_mark draws a <polyline> chevron), so it no longer mentions a gold core dot. The header logo follow-up is done (mkdocs.yml:16 logo: assets/mark.svg, built by geometry.mark), so that section is removed.
• Prose: the that-depends line on the home page now says "the older DI framework". The migration-guide sentence in the profile and on the home page is rewritten. The docs/standard.md opener is rewritten too.

Follow-ups, not changed here:

• MD1: chat-app's GitHub description ("Reference chat application showing modern-python libraries composed on a realistic domain") differs from its pyproject description.
• brand/build/projects.py::DOCS_REPOS social-card taglines are the old home page one-liners, for example httpware's "(retry, bulkhead)". Changing them means regenerating the social cards.

Checklist

• Lint and format pass (ruff) (this repo has no lint recipe)
• Type check passes (ty)
• Tests pass and new behavior is covered (uv run pytest: 172 passed; uv run mkdocs build --strict clean; scripts/check_site_content.sh passes; lychee --offline reports 0 errors)
• Build succeeds (uv build) if packaging or build config changed
• Repo metadata stays consistent across the three surfaces (GitHub description, pyproject description, profile blurb) if this touches packaging (except the chat-app GitHub description noted above)