Harden diagnostic response redaction

Redact every diagnostic response at the agent boundary, fail closed when sanitization cannot complete, and remove Windows, UNC, and slash-UNC paths from returned data. Preserve benign text while removing complete configured secret values, including nested JSON escapes and quoted HTML credential fields. Add focused regression coverage for collector errors, successful responses, support bundles, path variants, and punctuation secrets.

lib/diagnostics-collectors.js

@@ -20,18 +20,11 @@ function createCollectors(deps) {
   }
 
   function _deepRedact(value, secrets) {
-    const s = secrets || _secrets();
-    const walk = (v) => {
-      if (typeof v === 'string') return support.redactLogText(v, s);
-      if (Array.isArray(v)) return v.map(walk);
-      if (v && typeof v === 'object') {
-        const o = {};
-        for (const k of Object.keys(v)) o[k] = walk(v[k]);
-        return o;
-      }
-      return v;
-    };
-    try { return walk(value); } catch { return value; }
+    return support.valueScrub(value, secrets || _secrets());
+  }
+
+  function redactResponse(value) {
+    return _deepRedact(value);
   }
 
   function _resolveLogPath(name, backup) {
@@ -274,7 +267,7 @@ function createCollectors(deps) {
   return {
     getSystemInfo, getConfigRedacted, listLogs, readLog, getAppEvents,
     listErrors, getQueueState, getHistory, getRotationState, getHealth, serverHealth,
-    READABLE_LOGS
+    redactResponse, READABLE_LOGS
   };
 }