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

2 files changed, 16 insertions, 0 deletions

diff --git a/internal/db/migrations/blog/00007_post_image.sql b/internal/db/migrations/blog/00007_post_image.sql
new file mode 100644
index 0000000..75858a4
--- /dev/null
+++ b/internal/db/migrations/blog/00007_post_image.sql
@@ -0,0 +1,7 @@
+-- +goose Up
+-- A post's featured image: a library image shown as a thumbnail on listings
+-- and on the post page. Deleting the file just unsets it.
+ALTER TABLE posts ADD COLUMN image uuid REFERENCES files(id) ON DELETE SET NULL;
+
+-- +goose Down
+ALTER TABLE posts DROP COLUMN image;
diff --git a/internal/db/migrations/blog/00008_page_outro.sql b/internal/db/migrations/blog/00008_page_outro.sql
new file mode 100644
index 0000000..e795df0
--- /dev/null
+++ b/internal/db/migrations/blog/00008_page_outro.sql
@@ -0,0 +1,9 @@
+-- +goose Up
+-- A page can carry text after its posts as well as before them, in the same
+-- format as the intro (one format column per page).
+ALTER TABLE pages
+    ADD COLUMN outro_md   text NOT NULL DEFAULT '',
+    ADD COLUMN outro_html text NOT NULL DEFAULT '';
+
+-- +goose Down
+ALTER TABLE pages DROP COLUMN outro_md, DROP COLUMN outro_html;