test: bump remaining claude-opus-4-6 → 4-7 references

Mechanical model ID bump across the E2E eval suite. All six in-repo
files that referenced the older opus identifier are updated to match
the model gstack now defaults to. No behavior change beyond the model
ID the test harness asks for.

Contributed by @johnnysoftware7 (#1392).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/skill-e2e-review.test.ts

@@ -514,7 +514,7 @@ Analyze the git history and produce the narrative report as described in the SKI
       timeout: 300_000,
       testName: 'retro',
       runId,
-      model: 'claude-opus-4-6',
+      model: 'claude-opus-4-7',
     });
 
     logCost('/retro', result);