Offer supply suggestions, drop the circuit column, center cells

The Versorgung field suggests ELT and MSR (plus values already used in
the balance) through a datalist and still accepts free text. The circuit
number column is not needed in early design phases; it is removed from
the data model, the regenerated migration 0010, the editor and the
print. All cells are centered except "Verbraucher / Flächen", group
titles and total labels.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/estimate-balance.test.ts

@@ -52,7 +52,6 @@ function row(
     id: id(),
     sortOrder: 0,
     supply: "ELT",
-    circuitRef: null,
     name,
     quantity,
     unit: "piece",