refactor: add tool_error/tool_result helpers + read_raw_config, migrate 129 callsites

Add three reusable helpers to eliminate pervasive boilerplate:

tools/registry.py — tool_error() and tool_result():
  Every tool handler returns JSON strings. The pattern
  json.dumps({"error": msg}, ensure_ascii=False) appeared 106 times,
  and json.dumps({"success": False, "error": msg}, ...) another 23.
  Now: tool_error(msg) or tool_error(msg, success=False).

  tool_result() handles arbitrary result dicts:
  tool_result(success=True, data=payload) or tool_result(some_dict).

hermes_cli/config.py — read_raw_config():
  Lightweight YAML reader that returns the raw config dict without
  load_config()'s deep-merge + migration overhead. Available for
  callsites that just need a single config value.

Migration (129 callsites across 32 files):
- tools/: browser_camofox (18), file_tools (10), homeassistant (8),
  web_tools (7), skill_manager (7), cronjob (11), code_execution (4),
  delegate (5), send_message (4), tts (4), memory (7), session_search (3),
  mcp (2), clarify (2), skills_tool (3), todo (1), vision (1),
  browser (1), process_registry (2), image_gen (1)
- plugins/memory/: honcho (9), supermemory (9), hindsight (8),
  holographic (7), openviking (7), mem0 (7), byterover (6), retaindb (2)
- agent/: memory_manager (2), builtin_memory_provider (1)

tools/delegate_tool.py

@@ -527,7 +527,7 @@ def delegate_task(
     Returns JSON with results array, one entry per task.
     """
     if parent_agent is None:
-        return json.dumps({"error": "delegate_task requires a parent agent context."})
+        return tool_error("delegate_task requires a parent agent context.")
 
     # Depth limit
     depth = getattr(parent_agent, '_delegate_depth', 0)
@@ -552,7 +552,7 @@ def delegate_task(
     try:
         creds = _resolve_delegation_credentials(cfg, parent_agent)
     except ValueError as exc:
-        return json.dumps({"error": str(exc)})
+        return tool_error(str(exc))
 
     # Normalize to task list
     if tasks and isinstance(tasks, list):
@@ -560,15 +560,15 @@ def delegate_task(
     elif goal and isinstance(goal, str) and goal.strip():
         task_list = [{"goal": goal, "context": context, "toolsets": toolsets}]
     else:
-        return json.dumps({"error": "Provide either 'goal' (single task) or 'tasks' (batch)."})
+        return tool_error("Provide either 'goal' (single task) or 'tasks' (batch).")
 
     if not task_list:
-        return json.dumps({"error": "No tasks provided."})
+        return tool_error("No tasks provided.")
 
     # Validate each task has a goal
     for i, task in enumerate(task_list):
         if not task.get("goal", "").strip():
-            return json.dumps({"error": f"Task {i} is missing a 'goal'."})
+            return tool_error(f"Task {i} is missing a 'goal'.")
 
     overall_start = time.monotonic()
     results = []
@@ -958,7 +958,7 @@ DELEGATE_TASK_SCHEMA = {
 
 
 # --- Registry ---
-from tools.registry import registry
+from tools.registry import registry, tool_error
 
 registry.register(
     name="delegate_task",