16 tests covering all three failure modes:
- reasoningEffortMap xhigh→max for DeepSeek-family on any provider
- allowsSyntheticReasoningContentForToolCalls flag detection
- Tier 1: signature recovery from empty thinking blocks
- Tier 2: empty-string fallback when no thinking blocks exist
- Tier 3: synthetic placeholder for non-DeepSeek providers (Kimi)
Updates existing issue-883 tests to match new behavior (empty string
instead of synthetic "." for DeepSeek).
Burke T
ee7e6f67c1