refactor: rename the node from opencv-plot to dora-plot

The repository is dora-plot, but the package, the entrypoint, the manifest
name and the window title were all opencv-plot. Consumers wire the node by
`path:`, so the split name was visible in every dataflow.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018WLVZCFFcCH1EpTXGfS9aD

README.md

@@ -17,7 +17,7 @@ nodes:
     git: ssh://git@gitea.liria.cl:5001/liria/dora-plot.git
     tag: v0.1.0
     build: pip install .
-    path: opencv-plot
+    path: dora-plot
     inputs:
       image: camera/image
       bbox: detector/bbox
@@ -55,7 +55,7 @@ the camera and the viewer:
       - bbox
 
   - id: plot
-    path: opencv-plot
+    path: dora-plot
     build: pip install .
     inputs:
       image: camera/image
@@ -91,7 +91,7 @@ of that state:
 - An **`image`** event decodes the frame and immediately redraws: it draws every stored
   bbox (green rectangle plus `label, conf` text), draws the stored text at the top left,
   resizes to `PLOT_WIDTH`x`PLOT_HEIGHT` if both are set, and shows it in a window titled
-  `Dora Node: opencv-plot`. Press `q` in the window to quit.
+  `Dora Node: dora-plot`. Press `q` in the window to quit.
 - A **`bbox`** or **`text`** event only updates stored state; it is drawn on the next
   `image` redraw.