v0.2.0 — structured e-Factura authoring

✍️ anafpy can now author CIUS-RO invoices from scratch — no upstream invoicing system required.

Until now, e-Factura outbound was XML pass-through only: bring the complete
UBL XML your invoicing software exported. This release adds a second,
first-class path for callers with no upstream system of their own —
structured authoring (anafpy.efactura.authoring):

• One bidirectional flat model, InvoiceDocument, covers both invoices and
  credit notes (kind picks the render target), with computed totals and
  VAT breakdown (explicit overrides preserved).
• A hand-translated EN 16931 + CIUS-RO rule set (validate()) returns
  findings tagged with official BR-* rule ids — ANAF's own validare
  endpoint stays authoritative; this is a local, informational pre-check.
• Byte-stable round-trips: render_invoice / read_invoice / parse_invoice.
• Wired into EFacturaClient.upload_invoice (flat model → XML → upload) and
  the MCP server's two-step gated filing tools (efactura_prepare_invoice →
  efactura_submit), alongside the existing XML pass-through tools.
• The e-Factura inbox now reads downloads through the same strict
  read_invoice: DownloadedMessage.view never raises — None when the
  content isn't representable, with raw bytes and the full UBL model as the
  fallback tiers.
• A live-suite CIUS-RO drift tripwire files a minimal invoice via the
  authoring path and cross-checks local validate() verdicts against ANAF's
  own validare, so a future CIUS-RO revision announces itself.

As with everything in anafpy, the durable record of a filed invoice is the
caller's responsibility — ANAF's SPV purges filed messages after ~60 days;
it is not invoice storage. XML pass-through remains the strongly recommended
path whenever an upstream invoicing system already produces the document.

Install: pip install anafpy · pip install 'anafpy[mcp]'
Docs: https://anafpy.readthedocs.io/en/latest/library/authoring/