add a dora-node.yml manifest and a dora validate CI gate

No source package is shared between node repositories, so the manifest and its
type URNs are the only contract a consumer has. Declaring them makes a wiring
mistake fail at validate time with the producer and consumer URNs, instead of
at runtime.

Every payload this node sends is a raw buffer whose shape and dtype live in the
metadata rather than an Arrow struct, so the URNs name the element type:
UInt8 for image_bgr, Float32 for depth, camera_info and point_cloud, String for
camera_state. tick is UInt64, matching how dora types timer inputs.

dataflow.yml now builds the node from the checkout with path: + build:. A
git:-sourced node does not pick up an adjacent manifest, so validating the
previous form checked nothing; with path: the CLI reports "injected 6 contract
type(s)" and a deliberately mismatched annotation exits non-zero under
strict_types. The README keeps the tag: form for consumers.

The workflow needs no camera and no ZED SDK, since validation never runs the
node. Also ignores the git/ and out/ working directories dora build creates,
and drops the ignore rules for the deleted test assets.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y7g2cBJ5e3r15ZbJ9WZn8c

.gitea/workflows/validate.yml

@@ -0,0 +1,32 @@
+# Checks the dataflow against the typed contract in dora-node.yml. This runs no
+# node, so it needs neither a camera nor the ZED SDK.
+name: validate
+
+on: [push, pull_request]
+
+env:
+  DORA_VERSION: v1.0.1
+  DORA_TARGET: x86_64-unknown-linux-gnu
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install the dora CLI
+        run: |
+          curl -fsSL -o dora-cli.tar.gz \
+            "https://github.com/dora-rs/dora/releases/download/${DORA_VERSION}/dora-cli-${DORA_TARGET}.tar.gz"
+          tar xzf dora-cli.tar.gz
+          mkdir -p "$HOME/.local/bin"
+          install -m 755 "dora-cli-${DORA_TARGET}/dora" "$HOME/.local/bin/dora"
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+          rm -rf dora-cli.tar.gz "dora-cli-${DORA_TARGET}"
+
+      - run: dora --version
+
+      # strict_types: true in dataflow.yml turns a type warning into a non-zero
+      # exit, so a mismatched annotation fails here rather than at runtime.
+      - name: Validate the dataflow
+        run: dora validate dataflow.yml