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)

plugins/memory/byterover/__init__.py

@@ -27,6 +27,7 @@ from pathlib import Path
 from typing import Any, Dict, List, Optional
 
 from agent.memory_provider import MemoryProvider
+from tools.registry import tool_error
 
 logger = logging.getLogger(__name__)
 
@@ -320,7 +321,7 @@ class ByteRoverMemoryProvider(MemoryProvider):
             return self._tool_curate(args)
         elif tool_name == "brv_status":
             return self._tool_status()
-        return json.dumps({"error": f"Unknown tool: {tool_name}"})
+        return tool_error(f"Unknown tool: {tool_name}")
 
     def shutdown(self) -> None:
         if self._sync_thread and self._sync_thread.is_alive():
@@ -331,7 +332,7 @@ class ByteRoverMemoryProvider(MemoryProvider):
     def _tool_query(self, args: dict) -> str:
         query = args.get("query", "")
         if not query:
-            return json.dumps({"error": "query is required"})
+            return tool_error("query is required")
 
         result = _run_brv(
             ["query", "--", query.strip()[:5000]],
@@ -339,7 +340,7 @@ class ByteRoverMemoryProvider(MemoryProvider):
         )
 
         if not result["success"]:
-            return json.dumps({"error": result.get("error", "Query failed")})
+            return tool_error(result.get("error", "Query failed"))
 
         output = result.get("output", "").strip()
         if not output or len(output) < _MIN_OUTPUT_LEN:
@@ -354,7 +355,7 @@ class ByteRoverMemoryProvider(MemoryProvider):
     def _tool_curate(self, args: dict) -> str:
         content = args.get("content", "")
         if not content:
-            return json.dumps({"error": "content is required"})
+            return tool_error("content is required")
 
         result = _run_brv(
             ["curate", "--", content],
@@ -362,14 +363,14 @@ class ByteRoverMemoryProvider(MemoryProvider):
         )
 
         if not result["success"]:
-            return json.dumps({"error": result.get("error", "Curate failed")})
+            return tool_error(result.get("error", "Curate failed"))
 
         return json.dumps({"result": "Memory curated successfully."})
 
     def _tool_status(self) -> str:
         result = _run_brv(["status"], timeout=15, cwd=self._cwd)
         if not result["success"]:
-            return json.dumps({"error": result.get("error", "Status check failed")})
+            return tool_error(result.get("error", "Status check failed"))
         return json.dumps({"status": result.get("output", "")})