feat(cicontext): rules:changes: path-glob evaluation; 100% test coverage

- Add --changes PATH and --changes-from REF flags to glint check and glint graph
  for rules:changes: evaluation. --changes marks files explicitly; --changes-from
  runs git diff --name-only <REF> automatically. Both flags can be combined.
- Implement doublestar glob matching (*, ** across path segments) in EvalJob and
  EvalWorkflow; extended {paths, compare_to} map form supported.
- Without --changes/--changes-from the condition stays permissive (existing behaviour).
- Context summary line now shows changed-file count when file data is provided.
- Achieve 100% statement coverage: comprehensive tests added across all packages;
  removed provably dead code; added testability seams (exit, userHomeDirFn,
  execCommandOutput variables) to cover previously unreachable paths.

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

internal/resolver/includes.go

@@ -305,9 +305,6 @@ func substituteInputs(data []byte, inputs map[string]any) []byte {
 	}
 	return inputPlaceholderRe.ReplaceAllFunc(data, func(match []byte) []byte {
 		groups := inputPlaceholderRe.FindSubmatch(match)
-		if len(groups) < 2 {
-			return match
-		}
 		if val, ok := inputs[string(groups[1])]; ok {
 			return []byte(fmt.Sprintf("%v", val))
 		}