Merge the log and history into one page, group dishes by category

Kirjaa and Historia were two views of the same thing: every history row was
already a link back into the logger, and the logger had a day switcher. They
are now one page — the day being logged on top, history underneath, each row
loading its day into the logger above. Two tabs instead of three.

That also closed a gap. On an already-logged day there was no way to swap to
a different dish; "Muokkaa" only reopened the sides for the same one. It now
opens the board, so changing a dish and choosing one for the first time are
the same path.

Dishes are grouped by category on both screens, with Sekalaiset collecting
the ones covering more than one. That group is derived from the stored set
rather than being a fifth category, so a single Tortillat still satisfies
meat, chicken, fish and vegetarian at once when the §8.1 suggester arrives.

The two screens sort differently on purpose. The log board keeps frequency
then name inside each group, so favourites surface without wandering between
categories as counts change. The catalog sorts by name, because there you are
hunting a specific dish to edit rather than picking one to eat. groupDishes
preserves the order it is handed; the caller decides which it wants.

Ruoat is renamed Ruuat throughout, label and route both.

PRD.md

@@ -321,7 +321,7 @@ build and no asset bundler.
   lines of `database/sql`. There are no down-migrations: restoring the
   database file is the rollback for a single-household app.
 - **Bundle import**: the §7.3 mass import is a live feature of the running
-  app, on the Ruoat tab — paste JSON or upload a file, get a per-row report
+  app, on the Ruuat tab — paste JSON or upload a file, get a per-row report
   back. A plain multipart form rather than a Datastar round trip, since the
   response is a whole-page report and a form needs no client code. Uploads
   are capped at 1 MiB. The same importer is also reachable as