feat(cli): add shared PDF-to-image rendering and document usage

add shared render_pdf_pages helper for consistent rasterization
reuse the same renderer in regression test and CLI flow
add new render-image CLI command to export PDF pages as PNG
support single-page render (--page) and full export (--all-pages)
add configurable output path and DPI options
document the new rendering command and options in README

src/config_loader.py

@@ -64,6 +64,9 @@ def load_config(config_path: Path | None = None) -> Dict[str, Any]:
             f"config.json fehlen Pflichtfelder: {', '.join(missing)}"
         )
 
+    # Optional settings with backward-compatible defaults
+    data.setdefault("pdf_need_appearances", False)
+
     _config_cache = data
     _config_path_cache = config_path
     return data

src/pdf_filler.py

@@ -247,6 +247,14 @@ def fill_pdf(
 
         _apply_opt_mappings(fields, opt_maps)
 
+    SUMMARY_FIELDS_FOR_AP = (
+        "anwesend_sum",
+        "anwesend_gessum",
+        "pauschale_5_sum",
+        "pauschale_25_sum",
+        "pauschale_sum",
+    )
+
     writer = PdfWriter()
     writer.clone_document_from_reader(reader)
 
@@ -255,11 +263,24 @@ def fill_pdf(
 
     _update_widget_visibility(writer, fields)
 
-    # Tell the PDF viewer to regenerate appearance streams from field values.
-    # Without this flag, dropdown fields (plan, pauschale) display stale text
-    # instead of their actual selected option (e.g. "8,60" for pauschale).
+    # Second pass: regenerate AP only for summary text fields.
+    # This keeps footer/buttons visible with NeedAppearances=False while still
+    # rendering summary values in image-based comparisons.
+    summary_fields = {
+        name: fields[name]
+        for name in SUMMARY_FIELDS_FOR_AP
+        if name in fields
+    }
+    if summary_fields:
+        for page in writer.pages:
+            writer.update_page_form_field_values(page, summary_fields, auto_regenerate=True)
+
+    # Configure viewer-side appearance regeneration via config switch.
+    # Default is False for stable pymupdf rendering (footer/buttons visible).
     if "/AcroForm" in writer._root_object:
-        writer._root_object["/AcroForm"][NameObject("/NeedAppearances")] = BooleanObject(True)
+        writer._root_object["/AcroForm"][NameObject("/NeedAppearances")] = BooleanObject(
+            bool(config.get("pdf_need_appearances", False))
+        )
 
     output_path.parent.mkdir(parents=True, exist_ok=True)
     with output_path.open("wb") as fh:

src/pdf_render.py

@@ -0,0 +1,24 @@
+"""Shared PDF rasterization helpers used by tests and CLI."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import numpy as np
+import pymupdf
+
+
+def render_pdf_pages(pdf_path: Path, dpi: int = 150) -> list[np.ndarray]:
+    """Render all pages of *pdf_path* to RGB numpy arrays using pymupdf."""
+    zoom = dpi / 72.0
+    mat = pymupdf.Matrix(zoom, zoom)
+    doc = pymupdf.open(str(pdf_path))
+    images: list[np.ndarray] = []
+    for page in doc:
+        pix = page.get_pixmap(matrix=mat)
+        img = np.frombuffer(pix.samples, dtype=np.uint8).reshape(pix.h, pix.w, pix.n)
+        if pix.n == 4:
+            img = img[:, :, :3]
+        images.append(img.copy())
+    doc.close()
+    return images