ci: add dependabot for uv-managed Python projects (#545)

* ci: add dependabot for uv-managed Python projects

Configure weekly dependency updates for the two uv projects in the
repo — tools/yt-design-extractor and plugins/plugin-eval. Minor and
patch bumps are grouped per-project so each ecosystem produces at most
one rollup PR per week; majors arrive as individual PRs.

Native uv support is available in Dependabot since 2024 — it updates
pyproject.toml and uv.lock in lock-step.

* deps: drop include:scope to avoid double-parenthesized commit subject

With prefix "deps(yt-design-extractor)" + include:"scope", dependabot
would render commits as "deps(yt-design-extractor)(uv): bump foo from
1 to 2" — double parens. Drop include:scope on both ecosystem entries;
project identity stays in the prefix. Caught by the claude-code-review
workflow on PR #545.

.github/dependabot.yml

@@ -0,0 +1,42 @@
+# Dependabot config for the uv-managed Python projects in this repo.
+# See AGENTS.md for the canonical toolchain (uv + ruff + ty).
+#
+# Native uv support landed in GitHub Dependabot in 2024; the ecosystem
+# key is "uv" and Dependabot will update both pyproject.toml and uv.lock
+# in lock-step.
+
+version: 2
+updates:
+  # tools/yt-design-extractor — internal tooling
+  - package-ecosystem: "uv"
+    directory: "/tools/yt-design-extractor"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+    open-pull-requests-limit: 5
+    labels:
+      - "dependencies"
+    commit-message:
+      prefix: "deps(yt-design-extractor)"
+    groups:
+      python-minor-and-patch:
+        update-types:
+          - "minor"
+          - "patch"
+
+  # plugins/plugin-eval — plugin quality evaluation framework
+  - package-ecosystem: "uv"
+    directory: "/plugins/plugin-eval"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+    open-pull-requests-limit: 5
+    labels:
+      - "dependencies"
+    commit-message:
+      prefix: "deps(plugin-eval)"
+    groups:
+      python-minor-and-patch:
+        update-types:
+          - "minor"
+          - "patch"