fix(admin): shorten the receipt letter, show the account id

The receipt letter repeated what the receipt itself states. It now carries the
amount, the moment of payment with its offset, and the link — the receipt is
the document, and it opens without authentication, so there is nothing for the
two to disagree about. Subject reworded to name what it is.

The ledger and tax-export tables labelled the account link "card", meaning the
user card. On pages about payments that reads as a bank card, which is exactly
how it was misread. Both now show the first eight characters of the account id,
so the column carries data — two rows from the same buyer are visible at a
glance — while the link still holds the whole id.

.claude/CLAUDE.md

@@ -292,6 +292,10 @@ The native Android app is a Capacitor 8 wrapper of the `ui` SPA, scaffolded unde
     millisecond clock — the first eight are shared by every order in the same ~65 seconds, which
     would make two purchases indistinguishable to the probe. An unresolved outcome halts the
     whole queue on purpose; a blind retry is the one thing that must never happen.
+  - **The printable receipt link IS public** — `GET /api/v1/receipt/<ИНН>/<uuid>/print` opens with
+    no authentication (verified on prod 2026-07-28; online sources contradict each other on this,
+    so do not "fix" it back). It is the same URL the «Мой налог» app hands out under «копировать в
+    буфер», which is why the buyer's receipt letter can simply carry it.
   - **The receipt's time zone decides the tax month.** The ledger is UTC; `BACKEND_MYNALOG_TZ`
     (default `Europe/Moscow`) is what a payment is filed under, so a 23:30 UTC payment on the last
     of the month belongs to the *next* one.