fix: remove 115 verified dead code symbols across 46 production files

Automated dead code audit using vulture + coverage.py + ast-grep intersection,
confirmed by Opus deep verification pass. Every symbol verified to have zero
production callers (test imports excluded from reachability analysis).

Removes ~1,534 lines of dead production code across 46 files and ~1,382 lines
of stale test code. 3 entire files deleted (agent/builtin_memory_provider.py,
hermes_cli/checklist.py, tests/hermes_cli/test_setup_model_selection.py).

Co-authored-by: alt-glitch <balyan.sid@gmail.com>

hermes_cli/model_switch.py

@@ -915,74 +915,3 @@ def list_authenticated_providers(
     return results
 
 
-# ---------------------------------------------------------------------------
-# Fuzzy suggestions
-# ---------------------------------------------------------------------------
-
-def suggest_models(raw_input: str, limit: int = 3) -> List[str]:
-    """Return fuzzy model suggestions for a (possibly misspelled) input."""
-    query = raw_input.strip()
-    if not query:
-        return []
-
-    results = search_models_dev(query, limit=limit)
-    suggestions: list[str] = []
-    for r in results:
-        mid = r.get("model_id", "")
-        if mid:
-            suggestions.append(mid)
-
-    return suggestions[:limit]
-
-
-# ---------------------------------------------------------------------------
-# Custom provider switch
-# ---------------------------------------------------------------------------
-
-def switch_to_custom_provider() -> CustomAutoResult:
-    """Handle bare '/model --provider custom' — resolve endpoint and auto-detect model."""
-    from hermes_cli.runtime_provider import (
-        resolve_runtime_provider,
-        _auto_detect_local_model,
-    )
-
-    try:
-        runtime = resolve_runtime_provider(requested="custom")
-    except Exception as e:
-        return CustomAutoResult(
-            success=False,
-            error_message=f"Could not resolve custom endpoint: {e}",
-        )
-
-    cust_base = runtime.get("base_url", "")
-    cust_key = runtime.get("api_key", "")
-
-    if not cust_base or "openrouter.ai" in cust_base:
-        return CustomAutoResult(
-            success=False,
-            error_message=(
-                "No custom endpoint configured. "
-                "Set model.base_url in config.yaml, or set OPENAI_BASE_URL "
-                "in .env, or run: hermes setup -> Custom OpenAI-compatible endpoint"
-            ),
-        )
-
-    detected_model = _auto_detect_local_model(cust_base)
-    if not detected_model:
-        return CustomAutoResult(
-            success=False,
-            base_url=cust_base,
-            api_key=cust_key,
-            error_message=(
-                f"Custom endpoint at {cust_base} is reachable but no single "
-                f"model was auto-detected. Specify the model explicitly: "
-                f"/model <model-name> --provider custom"
-            ),
-        )
-
-    return CustomAutoResult(
-        success=True,
-        model=detected_model,
-        base_url=cust_base,
-        api_key=cust_key,
-    )