fix(export): paginate the archive size estimate and explain scope counts (#1635)

The period branch of estimateArchiveSize ran a single unpaginated
document read with one flat IN() over every posted entry id in the
year: past the PostgREST row cap it silently undercounts, and past a
few hundred entry ids the URL itself blows up. Chunk the id filter
(CHILD_FK_CHUNK) and paginate every read with fetchAllRows, mirroring
what writeDocuments already did (the ZIP content was never affected).

The dialog now says per scope which documents are counted: full
history includes unlinked inbox/receipt documents, a single year only
those linked to posted vouchers. Without that line, a company with
many unlinked receipts reads the count gap as a pagination bug.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

DECISIONS.md

@@ -1024,3 +1024,4 @@ One line per decision: `[YYYY-MM-DD] <decision>: <why>`. Appended by agents and
 [2026-08-16] Restyled QuickReviewDialog's inbox-picker trigger to the same full-width dropzone-footer row as TransactionBookingDialog even though it did not share the orphan-button layout: both surfaces come from #1620 and should present the same underlag affordance; the alternative (leaving a small outline button in one dialog and a footer row in the other) would split the visual language of one control. Presentation only, disabled-while-booking kept (PR #1628).
 [2026-08-17] Full-archive direct download resurfaced as an ImportRow + small centered dialog on /import's Exportera tab (row "Komplett arkiv", hash #full-archive), not by re-mounting the orphaned components/settings/BackupDownloadForm.tsx: the form was pre-frame card styling with a duplicate cloud-backup section, while the export tab's existing SIE dialog sets the house pattern (ImportRow -> sm:max-w-md dialog). Its logic (estimate, 413 handling, last-download stamp) ported into components/import/FullArchiveDialog.tsx; the orphan and its dead settings_backup_download i18n namespace deleted. The dialog reuses FiscalYearSelector despite design.md's "legacy, no new uses" line: FyPicker is a toolbar context chip, and the SIE dialog in the same file already uses FiscalYearSelector for the identical dialog-form slot, so matching it beats introducing a third pattern. Row gated to owner/admin because GET /api/reports/full-archive enforces that role server-side; showing members a download that can only 403 helps nobody.
 [2026-08-17] Article picker now overwrites the line's ROT/RUT (deduction_type + work_type) from the article's housework_type, INCLUDING clearing it when the article has none: article-defines-the-row is the established applyArticle semantic (description/price/unit already overwrite), and keeping a RUT flag when switching a row to a material article would silently claim a deduction on material (HUSFL labor-only rule). Kundkort personnummer prefill is a server-side fallback in buildInvoiceWriteData (typed > stored draft > kundkort), never a client prefill: customers.personal_number reaches the browser only as ciphertext/mask by design, so the editor just relaxes the required-mark and says where the number will come from.
+[2026-08-17] Arcim's "610 bilagor i Hela historiken men 100 i räkenskapsåret" in the full-archive dialog is NOT a pagination bug: verified against prod, exactly 100 documents are linked to posted vouchers in the single (extended) fiscal year and 510 are unlinked inbox/receipt docs, which scope=all includes by design (same split as cloud backup's year-ZIPs vs Grunddata.zip). Kept the semantics, fixed two things instead: estimateArchiveSize's period branch ran one unpaginated read with one flat IN() over every entry id (undercounts past the PostgREST row cap, URL blowup past ~a few hundred ids) -> now CHILD_FK_CHUNK-chunked and fetchAllRows-paginated like writeDocuments already was; and the dialog now states per scope which document set is counted, so the gap reads as intent, not as a bug.