fix(import): refuse a Bokio connection that opens a different company (#1315)

A Bokio integration token is scoped to one Bokio company and the company id is typed in by hand, so credentials for the user's other company imported that company's customers, suppliers and invoices with no error at all. Probe /companies/{id} before storing, mirroring the Bjorn Lunden /details probe, and refuse on a confident org-number mismatch.

Also surface the inbox mail body when nothing was attached: it was captured in email_body_text and never read back, which made Gmail's forwarding-confirmation mail unreadable and the forward impossible to complete.

messages/en.json

@@ -2714,7 +2714,9 @@
     "address_load_failed": "Could not read the inbox address, so we do not know whether the company already has one.",
     "items_load_failed": "Could not load the inbox, so we do not know whether anything is waiting here.",
     "document_loading": "Fetching the document…",
-    "document_load_failed": "The document is still stored but could not be shown right now."
+    "document_load_failed": "The document is still stored but could not be shown right now.",
+    "email_body_label": "Email content",
+    "email_body_empty": "The email had no text."
   },
   "tx_match_allocation": {
     "title": "Split payment",

messages/sv.json

@@ -2714,7 +2714,9 @@
     "address_load_failed": "Kunde inte läsa av inkorgsadressen, så vi vet inte om bolaget redan har en.",
     "items_load_failed": "Kunde inte läsa in inkorgen, så vi vet inte om det ligger något här.",
     "document_loading": "Hämtar underlaget…",
-    "document_load_failed": "Underlaget finns kvar men kunde inte visas just nu."
+    "document_load_failed": "Underlaget finns kvar men kunde inte visas just nu.",
+    "email_body_label": "Mejlets innehåll",
+    "email_body_empty": "Mejlet hade ingen text."
   },
   "tx_match_allocation": {
     "title": "Dela betalning",