I1: plan-eng-review-artifact names its report file without making it the only output

Runs 37151477069 and 37158847998 wrote the whole review, including the
GSTACK REVIEW REPORT, into review-output.md and never ran the Test Plan
Artifact block. #3017 made the artifact a hard assertion and dropped the
prompt's explicit artifact instruction, leaving 'Write your review to
review-output.md' as the one named destination. The prompt now names that
file as the selected report file and says every other output keeps the
destination the skill gives it, without naming the artifact.

test/skill-e2e-plan.test.ts

@@ -482,7 +482,7 @@ Proceed directly to the full review. Skip any AskUserQuestion calls — this is
 
 In this fixture the gstack state root is GSTACK_HOME=${gstackHome} and the project slug is ${slug}.
 
-Write your review to ${planDir}/review-output.md`,
+Use ${planDir}/review-output.md as the selected report file. Every other output keeps the destination the skill gives it.`,
       workingDirectory: planDir,
       env: { GSTACK_HOME: gstackHome },
       maxTurns: 25,