add camera_info input for the pinhole model

Nothing in a dataflow carries fx, fy, cx and cy except the camera, and every
pixel of a depth map needs them to become a 3D point. The node now accepts
them so whatever computes that next has them to hand.

They are read from two places because dora-zed publishes them twice: the
camera_info message, and the metadata of every frame. The per-frame copy is
not redundant -- camera_info goes out once per camera session, so a viewer
started after the camera would otherwise never see it, and reading frame
metadata means wiring the input is optional even for a camera that publishes
it.

A nine-element row-major K is accepted alongside the compact [fx, fy, cx, cy],
since that is how ROS spells the same model in sensor_msgs/CameraInfo.

The model is drawn under the caption rather than only stored. A depth map read
through the wrong intrinsics looks entirely plausible, and this is where that
becomes visible.

as_float32 moves to a payload module: camera_info arrives as a raw byte slice
for the same reason the depth map does, and the reinterpretation is now shared
rather than written twice.

Verified with dora-cli 1.0.1: validate passes with four contracts injected on
each side, the dataflow runs to a clean exit, and a composed frame was
rendered and inspected with the model drawn on it.

dora_image_view/main.py

@@ -1,7 +1,8 @@
 """A dora display sink: overlays bounding boxes and text on an image input.
 
-`image` and `depth` each fill one panel of the window and redraw. `bbox` and
-`text` events only update stored state, which the next redraw draws.
+`image` and `depth` each fill one panel of the window and redraw. `bbox`,
+`text` and `camera_info` events only update stored state, which the next redraw
+draws.
 """
 
 import argparse
@@ -10,7 +11,7 @@ import os
 import numpy as np
 from dora import Node
 
-from dora_image_view import bbox, decode, depth
+from dora_image_view import bbox, decode, depth, intrinsics
 from dora_image_view.view import View
 
 
@@ -37,6 +38,11 @@ def main() -> None:
         event_id = event["id"]
         metadata = event["metadata"]
 
+        # A sender that puts intrinsics on every frame keeps them current even
+        # if the camera_info message itself was published before this node
+        # started, which is when dora-zed sends it.
+        view.intrinsics = intrinsics.from_metadata(metadata) or view.intrinsics
+
         panel = _decode_panel(event_id, event["value"], metadata)
 
         if panel is not None:
@@ -44,6 +50,8 @@ def main() -> None:
             view.panels[name] = frame
             if view.show():
                 break
+        elif event_id == "camera_info":
+            view.intrinsics = intrinsics.parse(event["value"], metadata)
         elif event_id == "bbox":
             view.bboxes = bbox.parse(event["value"], metadata.get("format", "xyxy").lower())
         elif event_id == "text":