Retry invalid terminal reflection repairs

[HhhBZzz]

Summary

• Do not accept terminal reflection results that only cite the run without an event-level evidence reference.
• Retry when the first semantic repair still returns invalid reflection content, especially empty lesson.
• Update the initial/refinement prompts so provider-backed reflection no longer encourages empty lessons.

Test Plan

• mvn -q -Dtest=ProviderBackedTerminalReflectionGeneratorTest test
• mvn -q -Dtest=ProviderBackedTerminalReflectionGeneratorTest,TerminalMemoryExtractionServiceTest,MemoryProviderEvaluationHarnessServiceTest,MemoryExtractionTriggerTest,RuntimeMemoryEvaluationControllerTest,RuntimeMemoryCandidateControllerTest,MemoryCandidateReviewServiceTest test
• git diff --check

Context

After PR #42, local provider harness improved evidence grounding but still failed terminal reflection when the provider returned an empty lesson with valid evidence. This PR covers and repairs that second invalid-output mode.