Move caller dialog to Sonnet 4.6, add SearXNG for Devon, and fix stale model ids

Working-tree changes that had accumulated without being committed. The test
updates matter most: tests/test_caller_gen.py was left behind when caller_gen
started requiring voice and age in regulars_included, so the committed tree had
a failing suite that only passed locally.

- Caller dialog moves from Haiku 4.5 to Sonnet 4.6 (~$1/show to ~$3-4/show)
- Grok pinned to x-ai/grok-4.3; grok-4, grok-4-fast and grok-4.1-fast were
  retired from OpenRouter, and llm.py swallows the 404 and returns empty text,
  so a retired id makes callers go silent with nothing in the logs
- Devon's web_search now runs against SearXNG on the NAS
- Assorted TTS, audio, news, cost tracker and control-panel changes
- CLAUDE.md updated to match

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/services/regulars.py

@@ -39,6 +39,16 @@ class RegularCallerService:
     def get_regulars(self) -> list[dict]:
         return list(self._regulars)
 
+    def get_by_name(self, name: str) -> Optional[dict]:
+        """Find a regular by name (case-insensitive)."""
+        if not name:
+            return None
+        target = name.lower()
+        for r in self._regulars:
+            if r.get("name", "").lower() == target:
+                return r
+        return None
+
     def get_returning_callers(self, count: int = 2) -> list[dict]:
         """Get up to `count` regulars for returning caller slots"""
         import random