fix(telemetry): discover agents from ~/.openclaw/agents and clean docs

- Fallback to agent directory discovery when agents.json is absent
- Count configured agent workspaces (excluding main)
- Rewrite plugin docs to API key-only flow

server/telemetry.mjs

@@ -4,7 +4,7 @@
  * Runs as separate process from Gateway.
  * Collects system metrics and OpenClaw status, sends to Monitor.
  */
-import { readFile, access } from 'fs/promises';
+import { readFile, access, readdir } from 'fs/promises';
 import { constants } from 'fs';
 import { exec } from 'child_process';
 import { promisify } from 'util';
@@ -191,10 +191,24 @@ async function getOpenclawAgents() {
     try {
       await access(agentConfigPath, constants.R_OK);
       const data = JSON.parse(await readFile(agentConfigPath, 'utf8'));
-      return data.agents || [];
+      if (Array.isArray(data.agents) && data.agents.length > 0) {
+        return data.agents;
+      }
     } catch {
-      return [];
+      // fall through to directory-based discovery
     }
+
+    const agentsDir = `${CONFIG.openclawPath}/agents`;
+    await access(agentsDir, constants.R_OK);
+    const entries = await readdir(agentsDir, { withFileTypes: true });
+    return entries
+      .filter((entry) => entry.isDirectory())
+      .filter((entry) => entry.name !== 'main')
+      .map((entry) => ({
+        id: entry.name,
+        name: entry.name,
+        status: 'configured',
+      }));
   } catch {
     return [];
   }