test(persona): parameterize replay eval by backend/model (EVAL_BACKEND/EVAL_MODEL)

Lets the same safe-trigger prompts run through cloud, mi50 (Qwen), or
local (dolphin3:8b) for cross-model voice comparison.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01G796GsLCvJQKVN7hwV2cDx

scripts/persona_replay_eval.py

@@ -1,8 +1,12 @@
 """Replay the exact prompts where Lyra went 'too safe' through the rewritten persona.
 Run: `uv run python scripts/persona_replay_eval.py` (cloud backend; needs OPENAI_API_KEY).
+Pick a backend/model with env vars, e.g. `EVAL_BACKEND=mi50 uv run python …` or
+`EVAL_BACKEND=local EVAL_MODEL=dolphin3:8b uv run python …`.
 Eyeball each reply against the four tics: no menu, no tag-question closer, a side taken."""
 from __future__ import annotations
 
+import os
+
 from lyra import persona, llm
 
 # The real safe-trigger prompts from the diagnosed transcripts.
@@ -16,10 +20,13 @@ PROMPTS = [
 
 
 def main() -> None:
+    backend = os.getenv("EVAL_BACKEND", "cloud")
+    model = os.getenv("EVAL_MODEL") or None
     system = persona.core_prompt()
+    print(f"### backend={backend} model={model or '(default)'}")
     for i, p in enumerate(PROMPTS, 1):
         msgs = [{"role": "system", "content": system}, {"role": "user", "content": p}]
-        reply = llm.complete(msgs, backend="cloud", model=None)
+        reply = llm.complete(msgs, backend=backend, model=model)
         print(f"\n{'='*80}\n[{i}] USER: {p}\nLYRA: {reply}\n")