guides export/import bundles

CHANGELOG.md

@@ -22,6 +22,19 @@ ADR-007 and ADR-002.
   tables; in self-hosted mode one stored loan expands into a take and a return,
   so a returned drive is distinguishable from one still out.
 
+- **`flask guides export` / `flask guides import` - a guide can reach another
+  site.** Sites are separate databases and the ones that matter are air-gapped
+  from wherever a guide gets written, so a procedure written once was stranded
+  where it was typed. Export writes one `.guide.json` per guide with its images
+  carried inside it - one file, because a bundle that needs its images copied
+  alongside it is a bundle that will eventually arrive without them - and
+  import reads them back. The slug travels, since that is the address somebody
+  pastes into a work order and the same guide should answer to the same name on
+  every site; ids, revision history and publication state do not, because those
+  belong to the database that issued them. Imports arrive as drafts;
+  `--replace` updates a guide already carrying that slug rather than creating a
+  second one, which is how a corrected guide is re-shipped.
+
 - **`flask guides import-html` - an existing HTML article becomes a guide.**
   A site adopting this app arrives holding procedures already written: styled
   HTML pages that get mailed around and opened off a share. Retyping one into