Add a static image widget (PNG/JPEG/GIF/BMP/WEBP/TIFF/PDF upload)

A new widget type showing a single user-uploaded image with no live
upstream to poll -- decoded once at upload time (PDF's first page via
pypdfium2, BSD-3-Clause/Apache-2.0, no copyleft exposure) into plain RGB
PNG bytes, then composed per a crop/stretch/letterbox display mode like
the photos widget.

server/app/models.py

@@ -553,6 +553,27 @@ class WhiteboardWidgetConfig(Base):
     cached_image: Mapped[bytes | None] = mapped_column(LargeBinary, nullable=True)
 
 
+class StaticWidgetConfig(Base):
+    """One static-image widget's uploaded content + display settings --
+    unlike every other widget type, this one has no live upstream to
+    poll (Immich/CalDAV/WebDAV): the "source" is whatever the user last
+    uploaded (see routers/api_widgets.py's api_widget_static_upload,
+    app/image_upload.py), decoded once at upload time into plain RGB PNG
+    bytes so app/widgets/static_image.py's render() never re-runs
+    PDF/GIF decoding on every panel refresh."""
+
+    __tablename__ = "static_widget_configs"
+
+    widget_id: Mapped[int] = mapped_column(ForeignKey("widgets.id", ondelete="CASCADE"), primary_key=True)
+    image: Mapped[bytes | None] = mapped_column(LargeBinary, nullable=True)
+    original_filename: Mapped[str] = mapped_column(String, default="")
+    uploaded_at: Mapped[float] = mapped_column(Float, default=0.0)
+    # Same DISPLAY_MODES vocabulary as PhotoWidgetConfig.display_mode,
+    # minus crop_faces -- no face detection for an uploaded image (see
+    # image_pipeline.STATIC_DISPLAY_MODES).
+    display_mode: Mapped[str] = mapped_column(String, default="crop_fill")
+
+
 # widget_type -> its per-type extension table, keyed by widget_id. Used
 # by db.widget_locked() to resolve the right config row without importing
 # app/widgets/'s heavier render/action registry just for this lookup.
@@ -561,6 +582,7 @@ WIDGET_CONFIG_MODELS: dict[str, type] = {
     "calendar": CalendarWidgetConfig,
     "whiteboard": WhiteboardWidgetConfig,
     "tasks": TaskWidgetConfig,
+    "static": StaticWidgetConfig,
 }