Remove legacy startup configuration files and web assets

- Deleted startup.json, startup.json.linux, and startup.json.windows files to streamline configuration management.
- Removed web.config file as part of the cleanup process.
- Deleted jellyfin.svg and its compressed versions from the API documentation.
- Removed custom CSS files for ReDoc and Swagger documentation, including their compressed versions.

publish/wwwroot/api-docs/swagger/custom.css

@@ -1,17 +0,0 @@
-/* logo */
-.topbar-wrapper img[alt="Swagger UI"], .topbar-wrapper span {
-    visibility: collapse;
-}
-
-.topbar-wrapper .link:after {
-    content: '';
-    display: block;
-    background-image: url(../jellyfin.svg);
-    background-position: center;
-    background-repeat: no-repeat;
-    background-size: contain;
-    box-sizing: border-box;
-    width: 220px;
-    height: 40px;
-}
-/* end logo */