docs: reframe feature guides and mark experimental surfaces (#1760)

* docs: reframe feature guides and mark experimental surfaces

* fix: tighten task demo framing

* fix: validate experimental page status

* docs: anchor experimental office status

* fix(ci): isolate Wrangler preview install

* docs: complete focused camera example

* fix(ci): use valid Wrangler package name

scripts/validate-public-docs.mjs

@@ -803,6 +803,14 @@ function assertFrontmatter(file, markdown) {
       `${file} must start with YAML frontmatter containing title and description`,
     );
   }
+
+  const statusMatch = block.match(/^status:\s*(.*?)\s*$/m);
+  if (statusMatch) {
+    const status = statusMatch[1].replace(/^(["'])(.*)\1$/, "$2");
+    if (status !== "experimental") {
+      throw new Error(`${file} has unsupported page status: ${status}`);
+    }
+  }
 }
 
 /**