feat: optional device images in rack elevations, HTML preview in new tab

- New export option "Gerätebilder anzeigen": the SVG is rendered with
  include_images and the /media/ image links are replaced by embedded
  data URIs, since Word, WeasyPrint and SVG-as-image cannot load
  login-protected files. The Pillow PNG renderer draws the front/rear
  images too, with the device name on a dark label.
- Custom rack_svg_renderer adapters receive images=..., older adapters
  without that parameter keep working.
- The HTML preview now opens in a new browser tab.

Bump version to 0.3.0.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

netbox_customer_export/rack_svg.py

@@ -1,5 +1,7 @@
 """Rack-Ansichten offline (ohne HTTP-Aufruf der API) als SVG erzeugen."""
+import base64
 import logging
+import mimetypes
 
 from django.utils.module_loading import import_string
 from netbox.plugins import get_plugin_config
@@ -13,17 +15,52 @@ LEGEND_WIDTH = 30
 MARGIN_WIDTH = 15
 
 
-def render_rack_svg(rack, face, user):
+def device_image(device_type, face):
+    """Bilddatei (FieldFile) des Gerätetyps für die Seite oder None."""
+    image = getattr(device_type, "front_image" if face == "front" else "rear_image", None)
+    return image if image else None
+
+
+def _data_uri(image):
+    mime = mimetypes.guess_type(image.name)[0] or "image/png"
+    with image.open("rb") as f:
+        return f"data:{mime};base64,{base64.b64encode(f.read()).decode('ascii')}"
+
+
+def _inline_images(svg, devices):
+    """Ersetzt die /media/…-Links der Gerätebilder durch eingebettete Daten.
+
+    Word, WeasyPrint und <img src="data:image/svg+xml…"> laden keine externen (login-geschützten) Dateien nach.
+    """
+    seen = set()
+    for d in devices:
+        for face in ("front", "rear"):
+            image = device_image(d.device_type, face)
+            if not image or image.name in seen:
+                continue
+            seen.add(image.name)
+            try:
+                svg = svg.replace(f'"{image.url}"', f'"{_data_uri(image)}"')
+            except OSError:
+                logger.warning("Gerätebild %s nicht lesbar", image.name)
+    return svg
+
+
+def render_rack_svg(rack, face, user, images=False, devices=()):
     """Gibt (svg, fehler) zurück – genau einer der beiden Werte ist None.
 
     Ist ``rack_svg_renderer`` gesetzt (z.B. der Offline-Renderer aus Netbox-Utilities, der mehrere
-    Geräte pro HE korrekt darstellt), wird dieser aufgerufen: ``fn(rack=..., face=..., user=...)``.
+    Geräte pro HE korrekt darstellt), wird dieser aufgerufen: ``fn(rack=..., face=..., user=..., images=...)``.
     Andernfalls wird NetBox' eigener RackElevationSVG direkt in-process genutzt.
     """
     try:
         renderer = get_plugin_config("netbox_customer_export", "rack_svg_renderer")
         if renderer:
-            svg = import_string(renderer)(rack=rack, face=face, user=user)
+            fn = import_string(renderer)
+            try:
+                svg = fn(rack=rack, face=face, user=user, images=images)
+            except TypeError:  # ältere Adapter ohne images-Parameter
+                svg = fn(rack=rack, face=face, user=user)
         else:
             from dcim.svg import RackElevationSVG
 
@@ -36,10 +73,13 @@ def render_rack_svg(rack, face, user):
                 legend_width=LEGEND_WIDTH,
                 margin_width=MARGIN_WIDTH,
                 user=user,
-                include_images=False,
+                include_images=images,
                 base_url="",
             ).render(face)
-        return (svg.tostring() if hasattr(svg, "tostring") else str(svg)), None
+        svg = svg.tostring() if hasattr(svg, "tostring") else str(svg)
+        if images:
+            svg = _inline_images(svg, devices)
+        return svg, None
     except Exception as e:  # noqa: BLE001 – ein defektes Rack soll nicht den ganzen Export abbrechen
         logger.exception("Rack-SVG für %s (%s) fehlgeschlagen", rack, face)
         return None, f"{type(e).__name__}: {e}"