feat(confidence-engine): add CE-ULI-08 two-condition uncertainty comparison apparatus

Adds experimental apparatus for testing whether removing the question field
from importantUnknowns in reconstruction output improves semantic fidelity.

New files:
- lib/reconstruction/schema-variant.js (conditionB schema + production passthrough)
- prompts/reconstruct-v0.5-b-noreq.md (alt prompt, identical line count to prod)

Changed files:
- lib/graph/orchestrator.js (pass generationSchema through dependencies)
- lib/analysis.js (accept opts.generationSchema fallback to original schema)
- scripts/start-case-experiment-helper.cjs (--condition B/A flag support)
- tests/scripts/start-case-experiment-helper.test.js (8 new deterministic tests)

43 targeted deterministic tests PASS. Production callers use original prompt/schema unchanged.
No live model calls. No full suite evidence available.

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

lib/analysis.js

@@ -83,7 +83,7 @@ export async function analyseScenario(scenario, opts = {}) {
     const providerResult = await provider.generateReconstruction(
       promptObj.prompt,
       reconstructionModelName,
-      reconstructionGenerationJsonSchema,
+      opts.generationSchema ?? reconstructionGenerationJsonSchema,
       { outputZodSchema: reconstructionGenerationSchema },
     );
     if (