BlogApiController.PostBlog called Request.Form.Files
unconditionally, which throws on a plain JSON body — the
exception is "This request does not have a Content-Type header.
Forms are available from requests with bodies like POSTs and a
form Content-Type of either application/x-www-form-urlencoded or
multipart/form-data."
That broke PostIt's first-bill-of-blog flow: the client posts a
BlogPost as JSON and has no files to attach. The endpoint
contract is [FromBody] BlogPost, so the JSON body is deserialised
into 'blog' as expected — only the IFormFileCollection argument
to BlogSpotService.Create needs a real-or-empty value.
Branch on Request.HasFormContentType: pass the form files when
present, pass an empty FormFileCollection otherwise. BlogSpotService
already short-circuits on a null/empty file collection, so the
JSON-only path is now a clean code path.
Tests: add PostBlog_creates_a_post_and_Get_returns_it_in_the_list
(POST a draft, assert 201 + server-assigned Id, GET the index,
assert exactly one entry with that Id). Add a per-test
ResetDatabase helper because the in-memory store is shared across
the lifetime of the BlogsWebServerFixture instance.
BlogApiClient's "api/blog" path combined with the BaseAddress's
"api/v1/" prefix to produce 404s on every call. Drop the redundant
"api/" segment, let Save handle the create case (no selection) and
remove the now-redundant New button + command.
