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/gateway.py

@@ -316,8 +316,6 @@ def get_service_name() -> str:
     return f"{_SERVICE_BASE}-{suffix}"
 
 
-SERVICE_NAME = _SERVICE_BASE  # backward-compat for external importers; prefer get_service_name()
-
 
 def get_systemd_unit_path(system: bool = False) -> Path:
     name = get_service_name()
@@ -591,17 +589,6 @@ def get_python_path() -> str:
             return str(venv_python)
     return sys.executable
 
-def get_hermes_cli_path() -> str:
-    """Get the path to the hermes CLI."""
-    # Check if installed via pip
-    import shutil
-    hermes_bin = shutil.which("hermes")
-    if hermes_bin:
-        return hermes_bin
-    
-    # Fallback to direct module execution
-    return f"{get_python_path()} -m hermes_cli.main"
-
 
 # =============================================================================
 # Systemd (Linux)