Copy PDF URL now checks window.isSecureContext before using
navigator.clipboard, falls back to textarea+execCommand on HTTP,
and shows a success notification.
Invoice dropdown: Mark as Sent uses its own condition instead of
reusing Send, Resend hidden in detail view.
Estimate dropdown: Mark as Accepted/Rejected hidden when already in
the other terminal state, Convert to Invoice hidden on rejected
estimates. Added Convert to Estimate action for invoices.
fetchBasicMailConfig() was calling the wrong endpoint (company-config
instead of default config). Also, the response has no .data wrapper so
from_mail was never extracted. Fixed in all three send modals.
Estimate and payment preview blob construction now falls back to the
raw response when .data is undefined, matching the invoice modal.
