ci: add patterns: ['*'] to dependabot actions-minor-patch group (#407)

Gemini caught this post-merge on PR #406: Dependabot's `groups` block
requires at least one selection criterion (`patterns`, `exclude-patterns`,
or `dependency-type`) for the group to match any dependencies. Without
one, the group silently matches zero dependencies and every update opens
its own PR — defeating the purpose of grouping.

Added `patterns: ['*']` to match all GitHub Actions in the group, plus
an inline comment explaining why the selector is mandatory.

Author: ctrl-alt-automate

.github/dependabot.yml

@@ -33,6 +33,12 @@ updates:
     groups:
       actions-minor-patch:
         applies-to: version-updates
+        # Dependabot requires at least one of `patterns`, `exclude-patterns`,
+        # or `dependency-type` for the group to match anything. Without it,
+        # the group silently matches zero dependencies and every update
+        # opens its own PR — exactly the noise we meant to avoid.
+        patterns:
+          - "*"
         update-types:
           - "minor"
           - "patch"