fix the node manifest and make the example dataflow self-contained

Two problems, both found by the validate job once it could finally run.

categories named `teleop` and `input`, neither of which dora defines. The set is
fixed — sensor, actuator, robot, transform, filter, ml-inference, llm, speech,
communication, recorder, visualization, simulator, debug — and an unknown
variant makes the whole manifest unparseable, so every type annotation in it was
being ignored.

dataflow.yml spanned three repositories through sibling paths, which meant dora
could not resolve the other nodes' manifests and reported their typed outputs as
unannotated. It also could not be validated in CI, which clones one repo. The
house pattern is a self-contained dataflow, and this now follows it: teleop plus
a bench stand-in for the arm and the browser, both from this checkout. The real
three-node wiring moves to README.md, where a consumer would look for it.

The bench answers every service, publishes plausible telemetry, and prints the
velocities it is sent, so the node can be driven from a real gamepad with no
robot in the room. It is not a simulator and must not become one: it never
integrates a velocity or moves a pose.

examples/dora-node.yml

@@ -0,0 +1,42 @@
+# Manifest for the bench stand-in.
+#
+# dora resolves a node's manifest from its `path:`, so without this file the
+# bench would be validated against the teleop node's own contract and every port
+# would look wrong.
+
+apiVersion: 1
+name: bench
+namespace: liria
+description: Bench stand-in for the arm and the browser, so teleop can run with neither
+
+runtime: python
+entrypoint: bench.py
+dora: ">=1.0"
+
+inputs:
+  tick:
+    description: Drives the telemetry the arm node would publish.
+    type: std/core/v1/UInt64
+  jog:
+    description: A velocity teleop wants the arm to move at. Printed, then forgotten.
+  request:
+    description: A service call. Every one is answered ok.
+  ui_state:
+    description: >-
+      The console snapshot teleop publishes. Accepted and dropped: no browser is
+      attached to this dataflow.
+
+outputs:
+  response:
+    description: One answer per request, under the id it arrived with.
+  robot_state:
+    description: Reports `ready` once, so teleop stops drawing the arm as disconnected.
+    type: std/core/v1/String
+  tcp_pose:
+    description: A fixed tool-tip pose. Fixed on purpose — nothing here integrates a velocity.
+    type: std/core/v1/Float32
+  joint_pose:
+    description: Fixed joint angles, for the same reason.
+    type: std/core/v1/Float32
+  clients:
+    description: Always zero connected, since the WebSocket bridge is not in this dataflow.