chore(deps): add Dependabot config for pip, Docker, and GitHub Actions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/dependabot.yml

@@ -0,0 +1,35 @@
+version: 2
+updates:
+  - package-ecosystem: "pip"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+    open-pull-requests-limit: 10
+    groups:
+      llm-providers:
+        patterns:
+          - "litellm"
+          - "openai"
+          - "anthropic"
+      testing:
+        patterns:
+          - "pytest*"
+      linting:
+        patterns:
+          - "black"
+          - "ruff"
+
+  - package-ecosystem: "docker"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+    open-pull-requests-limit: 5
+
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+      day: "monday"
+    open-pull-requests-limit: 5