fix(import): fit the account mapping table at 100 % zoom (#2125) (#2138)

The SIE-import mapping table was a fixed layout of 1216px, with 144px
spent on a four-digit source account and the VAT cell's min-w-72
overflowing 32px into Konfidens, so on a laptop content column it
scrolled sideways and read as cramped even after #1684 kept the confirm
button reachable.

- Column budget ~990px: Källkonto w-20, Källnamn w-40 (existing
  truncate + tooltip), arrow w-8, Målkonto w-56, VAT w-72 with the
  treatment select flex-1/min-w-0 and the rate select shrink-0,
  Konfidens w-24, Bekräfta w-28.
- 13px text and px-3 cells, matching the page-level list density.
- Bekräfta is an icon-only button (Check) with a tooltip; the header
  keeps the label and gains an InfoTooltip explaining what confirming
  does (new chart_of_accounts.vat_treatment_confirm_help, sv + en).

Closes #2125


Claude-Session: https://claude.ai/code/session_01WFhSQWzu5SyXB6kG5ActZc

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

messages/en.json

@@ -5597,7 +5597,8 @@
     "vat_review_confirm_all": "Confirm all suggested ({count})",
     "vat_review_filter": "{count} VAT treatments to review",
     "vat_treatment_column": "VAT treatment",
-    "vat_treatment_confirm": "Confirm"
+    "vat_treatment_confirm": "Confirm",
+    "vat_treatment_confirm_help": "Accept the VAT code for this row to mark it as reviewed. Change the VAT code or rate first if the suggestion is wrong."
   },
   "dimensions": {
     "new_value": "New value",

messages/sv.json

@@ -5597,7 +5597,8 @@
     "vat_review_confirm_all": "Bekräfta alla föreslagna ({count})",
     "vat_review_filter": "{count} momskoder att granska",
     "vat_treatment_column": "Momskod",
-    "vat_treatment_confirm": "Bekräfta"
+    "vat_treatment_confirm": "Bekräfta",
+    "vat_treatment_confirm_help": "Godkänn momskoden för raden så räknas den som granskad. Ändra momskod eller momssats först om förslaget inte stämmer."
   },
   "dimensions": {
     "new_value": "Nytt värde",