Check XML sitemap health

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "domain": {
+      "description": "The hostname the sitemap was checked for.",
+      "type": "string"
+    },
+    "fetched_at": {
+      "description": "UTC ISO-8601 timestamp of the check.",
+      "type": "string"
+    },
+    "findings": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "category": {
+            "description": "Finding category - which AI-SEO dimension it relates to.",
+            "enum": [
+              "schema",
+              "robots",
+              "technical",
+              "freshness",
+              "structure",
+              "authority",
+              "presence",
+              "sitemap",
+              "llms_txt",
+              "citation",
+              "evidence",
+              "trust",
+              "entity",
+              "content"
+            ],
+            "type": "string"
+          },
+          "estimated_impact": {
+            "description": "Estimated impact on AI citation probability when resolved.",
+            "enum": [
+              "high",
+              "medium",
+              "low"
+            ],
+            "type": "string"
+          },
+          "failure_signal": {
+            "description": "Falsifiability: the observable signal that would prove the fix did NOT work.",
+            "type": "string"
+          },
+          "fix": {
+            "description": "Concrete, copy-pasteable fix.",
+            "type": "string"
+          },
+          "leading_indicator": {
+            "description": "Falsifiability: the leading indicator to monitor to confirm the fix is landing.",
+            "type": "string"
+          },
+          "message": {
+            "description": "Human-readable description of the issue.",
+            "type": "string"
+          },
+          "severity": {
+            "description": "Triage priority: critical blocks AI citation, warning hurts probability, info is nice-to-have.",
+            "enum": [
+              "critical",
+              "warning",
+              "info"
+            ],
+            "type": "string"
+          },
+          "where": {
+            "description": "Location of the issue (CSS selector, JSON-LD path, robots.txt line, or 'page-level').",
+            "type": "string"
+          }
+        },
+        "required": [
+          "severity",
+          "category",
+          "where",
+          "message",
+          "fix"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "sitemap_url": {
+      "description": "Resolved sitemap URL (null when status != found).",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "status": {
+      "description": "Outcome of the sitemap lookup.",
+      "enum": [
+        "found",
+        "missing",
+        "error"
+      ],
+      "type": "string"
+    },
+    "total_urls": {
+      "description": "Total URLs declared across the sitemap (and indexed children).",
+      "type": "number"
+    },
+    "urls_with_lastmod": {
+      "description": "Count of URLs that carry a lastmod attribute.",
+      "type": "number"
+    }
+  },
+  "required": [
+    "domain",
+    "fetched_at",
+    "status",
+    "sitemap_url",
+    "total_urls",
+    "urls_with_lastmod",
+    "findings"
+  ],
+  "type": "object"
+}

Added value: +"Hostname or origin to inspect. Examples: `example.com`, `https://example.com`. The tool tries `/sitemap.xml` then the sitemap URL declared in robots.txt; follows sitemap index files one level deep. Read-only HTTP GETs against the domain only."

Added value: +"Cap on how many URLs from the sitemap to sample for lastmod, image/video extension, and structural checks. Default 100. Increase up to 500 for large sites where you want a more representative sample; each extra URL is one HTTP HEAD."