Add post summaries, featured images and a page outro

Recreating gizmolab.net as a blog showed three things the design system
could not express, all of them ordinary blog features:

- Listings can show a summary and a "Read more" link instead of the whole
  post (theme.list_style). The summary is the source up to <!--more-->;
  without the marker a Markdown post is cut at a block boundary after 70
  words (never inside a code fence) and an HTML post is shown whole, since
  cutting hand-written markup blind would leave tags open. Computed at
  render time (Post.Excerpt/HasMore), nothing new is stored.
- A post can carry a featured image (posts.image, a library file that is
  unset when the file is deleted): a thumbnail floated beside the entry on
  listings, and on the post page above or below the text, or not at all,
  as theme.post_image says. The picker is the design page's imagepick; its
  library panel moves out of design.html into partials/imagelib.html so
  both forms share it — which also removes a stale pickAction call the
  design form's click handler would have hit.
- A page can have a closing text after its posts (pages.outro_md/html), in
  the intro's format: the per-page counterpart of the blog-wide "after the
  posts" module, for a home page that ends in a site map or a widget. The
  editor partial takes formatof to share another editor's Format row, and
  its upload field is now <name>_file so two editors fit in one form.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Sd8UPWrvyYCLj97JexNw3A

1 files changed, 45 insertions, 0 deletions

diff --git a/internal/web/web_test.go b/internal/web/web_test.go
index aa9b78e..a13697c 100644
--- a/internal/web/web_test.go
+++ b/internal/web/web_test.go
@@ -635,3 +635,48 @@ func TestNormalizeSection(t *testing.T) {
 		t.Errorf("half-valid placement: %+v", sec)
 	}
 }
+
+func TestPostSummary(t *testing.T) {
+	md := func(s string) *store.Post {
+		return &store.Post{Format: store.FormatMarkdown, BodyMD: s, BodyHTML: renderBody(store.FormatMarkdown, s)}
+	}
+	// the marker wins, whatever the length
+	p := md("first\n\n<!--more-->\n\nsecond")
+	if html, more := postSummary(p); !more || !strings.Contains(html, "first") || strings.Contains(html, "second") {
+		t.Errorf("marker: got %q, %v", html, more)
+	}
+	// short posts are shown whole
+	if html, more := postSummary(md("just a line")); more || html != p.BodyHTML && !strings.Contains(html, "just a line") {
+		t.Errorf("short: got %q, %v", html, more)
+	}
+	// a long one is cut at a block boundary after summaryWords words
+	long := strings.Repeat("word ", 50) + "\n\n" + strings.Repeat("word ", 50) + "\n\nlast block"
+	if html, more := postSummary(md(long)); !more || strings.Contains(html, "last block") || strings.Count(html, "word") != 100 {
+		t.Errorf("auto cut: got %d words, more=%v", strings.Count(html, "word"), more)
+	}
+	// never inside a code fence
+	fenced := "intro\n\n```\n" + strings.Repeat("code ", 80) + "\n\nstill code\n```\n\nafter"
+	if html, more := postSummary(md(fenced)); !more || !strings.Contains(html, "still code") || strings.Contains(html, "after") {
+		t.Errorf("fence: got %q, %v", html, more)
+	}
+	// HTML posts are only cut at the marker
+	h := &store.Post{Format: store.FormatHTML, BodyMD: "<div>" + strings.Repeat("w ", 200) + "</div>"}
+	h.BodyHTML = h.BodyMD
+	if html, more := postSummary(h); more || html != h.BodyHTML {
+		t.Errorf("html: cut without a marker")
+	}
+	h.BodyMD = "<p>a</p><!--more--><p>b</p>"
+	if html, more := postSummary(h); !more || html != "<p>a</p>" {
+		t.Errorf("html marker: got %q, %v", html, more)
+	}
+	// fillExcerpts follows the theme
+	posts := []store.Post{*md(long)}
+	fillExcerpts(Theme{ListStyle: "full"}, posts)
+	if posts[0].HasMore || posts[0].Excerpt != posts[0].BodyHTML {
+		t.Error("full: excerpt should be the whole body")
+	}
+	fillExcerpts(Theme{ListStyle: "summary"}, posts)
+	if !posts[0].HasMore {
+		t.Error("summary: expected a cut")
+	}
+}