Close functional regressions found by comparing the legacy applications
(Intranet_Legacy/) against their C# counterparts:
- ProcessWebComService: send attachments inline (base64) with the
push_com POST so invoice/reminder PDFs are attached again.
- FuchsPdf: wire GetPaycode into ApplyInvoice/ApplyReminder to restore
the SEPA giro-code payment QR, and restore the full standard invoice
text block (§35a labor-cost note, Akonto text, §14/§48 notes, AGB,
Steuernummer, Verrechnungssätze, etc.).
- IntranetController: restore changepassword validation (password
strength, confirmation match, current-password verification) and the
mfr empty-id OData $metadata response.
- Reports: port the ocms_visualization engine to C# (FuchsVisualization)
and wire FuchsReports.ProcessFdsRequest to render generic/
generic_content/chart reports instead of returning an empty OK stub.
Adds smoke tests for the giro QR generator and report page builder.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>