feat: implement MCP proxy for OpenClaw tool access in contractor agent

Complete the MCP tool call chain:
- contractor-agent bridge exposes /mcp/execute endpoint for tool callbacks
- openclaw-mcp-server.mjs proxies OpenClaw tool defs to Claude as MCP tools
- sdk-adapter passes --mcp-config on first turn with all OpenClaw tools
- tool-test plugin registers contractor_echo in globalThis tool handler map
- agent-config-writer auto-sets tools.profile=full so OpenClaw sends tool defs
- Fix --mcp-config arg ordering: prompt must come before <configs...> flag

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

openclaw.plugin.json

@@ -0,0 +1,28 @@
+{
+  "id": "contractor-agent",
+  "name": "Contractor Agent",
+  "version": "0.1.0",
+  "description": "Turns Claude Code into an OpenClaw-managed contractor agent",
+  "main": "src/index.ts",
+  "configSchema": {
+    "type": "object",
+    "additionalProperties": false,
+    "properties": {
+      "bridgePort": {
+        "type": "number",
+        "default": 18800,
+        "description": "Port for the contractor bridge sidecar HTTP server"
+      },
+      "bridgeApiKey": {
+        "type": "string",
+        "default": "contractor-bridge-local",
+        "description": "API key for the bridge sidecar (local use only)"
+      },
+      "permissionMode": {
+        "type": "string",
+        "default": "bypassPermissions",
+        "description": "Claude Code permission mode for contractor sessions"
+      }
+    }
+  }
+}