perf: pin quality tests to Opus, add --retry 2 and test:e2e:fast tier

~10 quality-sensitive tests (planted-bug detection, design quality judge,
strategic review, retro analysis) explicitly pinned to Opus. ~30 structure
tests default to Sonnet for 5x speed improvement.

Added --retry 2 to all E2E scripts for flaky test resilience.
Added test:e2e:fast script that excludes 8 slowest tests for quick feedback.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

test/skill-e2e-plan.test.ts

@@ -81,6 +81,7 @@ Focus on reviewing the plan content: architecture, error handling, security, and
       timeout: 360_000,
       testName: 'plan-ceo-review',
       runId,
+      model: 'claude-opus-4-6',
     });
 
     logCost('/plan-ceo-review', result);
@@ -165,6 +166,7 @@ Focus on reviewing the plan content: architecture, error handling, security, and
       timeout: 360_000,
       testName: 'plan-ceo-review-selective',
       runId,
+      model: 'claude-opus-4-6',
     });
 
     logCost('/plan-ceo-review (SELECTIVE)', result);
@@ -257,6 +259,7 @@ Focus on architecture, code quality, tests, and performance sections.`,
       timeout: 360_000,
       testName: 'plan-eng-review',
       runId,
+      model: 'claude-opus-4-6',
     });
 
     logCost('/plan-eng-review', result);
@@ -382,6 +385,7 @@ Write your review to ${planDir}/review-output.md`,
       timeout: 360_000,
       testName: 'plan-eng-review-artifact',
       runId,
+      model: 'claude-opus-4-6',
     });
 
     logCost('/plan-eng-review artifact', result);

test/skill-e2e-qa-bugs.test.ts

@@ -100,6 +100,7 @@ CRITICAL RULES:
       timeout: 300_000,
       testName: `qa-${label}`,
       runId,
+      model: 'claude-opus-4-6',
     });
 
     logCost(`/qa ${label}`, result);

test/skill-e2e-review.test.ts

@@ -510,6 +510,7 @@ 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',
     });
 
     logCost('/retro', result);