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-design.test.ts

@@ -103,7 +103,7 @@ Write DESIGN.md and CLAUDE.md (or update it) in the working directory.`,
       timeout: 360_000,
       testName: 'design-consultation-core',
       runId,
-      model: 'claude-opus-4-6',
+      model: 'claude-opus-4-7',
     });
 
     logCost('/design-consultation core', result);
@@ -227,7 +227,7 @@ Skip research. Skip font preview. Skip any AskUserQuestion calls — this is non
       timeout: 360_000,
       testName: 'design-consultation-existing',
       runId,
-      model: 'claude-opus-4-6',
+      model: 'claude-opus-4-7',
     });
 
     logCost('/design-consultation existing', result);