Align the project hero with the showcase design: owner cover, logo, repo link

The hero now matches the showcase reference: the title block, tagline
(first description line), type/platform chips, author row and started
date render OVERLAID on the cover banner behind a bottom scrim, with
the optional project logo as a framed tile beside them and the Visit
Website CTA on the right. The section tab bar switches to the underline
style with Overview active.

Owners control the missing pieces from the create and edit modals,
which are now multipart: cover_image and logo_image file uploads
(stored as bare uploaded filenames via save_inline_image, the
posts.image pattern; a new upload replaces the previous one) plus a
repo_url sibling of website_url (same normalization/validation). The
cover feeds og:image and the schema image, the logo becomes schema
thumbnailUrl, and sameAs now carries website + repository. repo_url
rides ProjectOut, the Devii create/edit actions and the API docs;
tests cover repo normalization, the multipart upload round-trip and
the hero render.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/unit/models.py

@@ -57,6 +57,7 @@ def test_project_form_website_url_normalizes_and_validates():
         ProjectForm(**base, website_url="http://x.dev/a?b=1").website_url
         == "http://x.dev/a?b=1"
     )
+    assert ProjectForm(**base, repo_url="github.com/me/x").repo_url == "https://github.com/me/x"
     assert normalize_website_url("  ") == ""
     with pytest.raises(ValidationError):
         ProjectForm(**base, website_url="javascript:alert(1)")