fix(documents): close v1.25.1 library QA findings (backend)

Default documentDate at store time. A store-only upload no longer lands
with a NULL filing date: when the client omits one, default it to the
upload day so the column is always set on a stored row. The library list
sorts, groups, and range-filters on the same effective date the UI shows,
so undated uploads no longer mis-sort under nulls-last, break date-group
headers, or fall through the range filter. The date stays user-editable
and may be cleared back to NULL via PATCH.

Block re-extraction once any fact is APPROVED. A partially-confirmed
document stays EXTRACTED, which the CONFIRMED guard does not catch;
re-extracting would delete the approved facts (severing the committed
record's provenance) and re-stage them as PENDING, letting a second
approval duplicate the committed lab / condition / medication. The
extract route now refuses with 409 (documents.inbound.alreadyPartlyConfirmed)
when approved facts exist; the user must finish reviewing or discard first.

RFC 5987-encode the original-download filename. The Content-Disposition
now carries both an ASCII filename= fallback and a filename*=UTF-8'' value
so a non-ASCII name survives intact; the stored set is inline-safe by
construction, so the dead attachment branch is removed.

Add a light per-user rate-limit backstop to the original-read, PATCH, and
DELETE routes (generous; self-DoS only — the routes are owner-scoped).

Lean the list counts: tally facts for the whole page in one grouped count
instead of materialising fact-id rows, and exclude REJECTED facts from
factCount. Extend the documentDate index with deleted_at to cover the
list scan. Document the deliberate plaintext-title PHI tradeoff at the
column and the store site.

src/lib/validations/inbound-documents.ts

@@ -212,7 +212,9 @@ export interface InboundDocumentDto {
   /** User-set filing date (YYYY-MM-DD), or null. */
   documentDate: string | null;
   errorReason: string | null;
+  /** Count of the document's non-REJECTED staged facts. */
   factCount: number;
+  /** Count of staged facts still PENDING review. */
   pendingCount: number;
   createdAt: string;
   updatedAt: string;