Move PDF generation from synchronous publish flow to a background polling
job. Published versions with file_id IS NULL are picked up by the job,
which generates the PDF, uploads to S3, and links the file. Export PDF
now serves stored files for published versions (with optional signature
page and watermark) and generates on the fly for drafts.
Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>
Move document download/view to a dedicated viewer page with PDF preview,
access request flow, and a proper 404 error boundary when documents are
not found. The backend now returns NOT_FOUND instead of INTERNAL for
missing documents and reports.
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
