v0.6 - model-tier router, central config, verdict-driven human review
Adds a model-tier router (UnifiedLLMClient) on top of the Gemini retry/
rotation spine, with tiered fallback and per-call cost accounting, plus a
single src/config.py for every tunable value. Human-review verdicts now drive
the report status, rule learning and the CI exit code through one shared path.
Scoring is multiplicative and citation verification is whitespace-safe.
Built on the v0.2-v0.5 line.