feat: reorganize to standard OpenClaw plugin structure

New structure:
├── package.json                 # Root package
├── README.md                    # Documentation
├── plugin/                      # OpenClaw plugin
│   ├── openclaw.plugin.json     # Plugin manifest
│   ├── index.ts                 # Plugin entry (TypeScript)
│   ├── package.json
│   └── tsconfig.json
├── server/                      # Telemetry sidecar
│   └── telemetry.mjs
├── skills/                      # OpenClaw skills
└── scripts/
    └── install.mjs              # Installation script

Matches PaddedCell project structure.
Provides install.mjs with build/install/configure/uninstall commands.

plugin/openclaw.plugin.json

@@ -0,0 +1,48 @@
+{
+  "id": "harborforge-monitor",
+  "name": "HarborForge Monitor",
+  "version": "0.1.0",
+  "description": "Server monitoring plugin for HarborForge - streams telemetry to Monitor",
+  "entry": "./index.js",
+  "configSchema": {
+    "type": "object",
+    "additionalProperties": false,
+    "properties": {
+      "enabled": { 
+        "type": "boolean", 
+        "default": true,
+        "description": "Enable the monitor plugin"
+      },
+      "backendUrl": { 
+        "type": "string", 
+        "default": "https://monitor.hangman-lab.top",
+        "description": "HarborForge Monitor backend URL"
+      },
+      "identifier": { 
+        "type": "string",
+        "description": "Server identifier (auto-detected from hostname if not set)"
+      },
+      "challengeUuid": { 
+        "type": "string",
+        "description": "Registration challenge UUID from Monitor"
+      },
+      "reportIntervalSec": { 
+        "type": "number", 
+        "default": 30,
+        "description": "How often to report metrics (seconds)"
+      },
+      "httpFallbackIntervalSec": { 
+        "type": "number", 
+        "default": 60,
+        "description": "HTTP heartbeat interval when WS unavailable"
+      },
+      "logLevel": { 
+        "type": "string", 
+        "enum": ["debug", "info", "warn", "error"], 
+        "default": "info",
+        "description": "Logging level"
+      }
+    },
+    "required": ["challengeUuid"]
+  }
+}