Add native Opgroeien Groeipakket caseload and expenditure facts

[MaxGhenis]

Refs #69.

Source gap

The current opgroeien-groeipakket-caseload-2025 package is a curated extract
of heterogeneous headline figures. It does not pin a native publisher export,
does not include expenditure, and labels the whole administrative scope as
NUTS BE2 without publisher-byte evidence that every row has that geography.

Opgroeien's official Cijfers op maat page embeds separate Power BI reports
for Groeipakket caseload and budget/expenditure. The current execution
environment cannot retrieve their native data exports. Rendered dashboard
cards, screenshots, accessibility text, and manual transcription are not
acceptable Chronicle artifacts.

Deterministic handoff

Use the two Opgroeien entries in
FETCH-MANIFEST-BELGIUM-PUBLIC-FACTS.json:

• official landing page:
  https://www.opgroeien.be/kennis/cijfers-en-onderzoek/groeipakket/cijfers-op-maat
• caseload report ID and exact native-export procedure recorded in the handoff;
• expenditure report ID and exact native-export procedure recorded in the
  handoff.

Acceptance criteria

• Pin unchanged native publisher export bytes with URL, SHA-256, size, report
  vintage/update timestamp, visual name, active filters, headers, and
  content-addressed raw-storage pointer.
• Preserve each publisher reference period, recipient unit, component,
  currency/scale, and administrative/geographic scope exactly.
• Add post-2019 caseload and expenditure facts only for cells that resolve from
  the pinned export. Do not force administrative coverage to BE2 without
  evidence in the export.
• Do not calculate annual totals, per-recipient amounts, reconciliations,
  imputed periods, take-up, or model bindings.
• Run validate-package, source-cell preservation, fact-load,
  consumer-artifact, raw-facts-boundary, ruff, and git diff --check checks.