feat(cli): Complete the check rule catalog

Add D002 (malformed attribute blocks), R004 (skipped declare rows), and V001-V005 (CSV data files). CSV checks run once per referenced file and also cover inline spark-table bodies.

Generate docs/reference.md from the known.ts catalog via npm run gen:reference, and add drift guards asserting the catalog matches the customElement call sites and the committed reference.

src/cli/validate/known.test.ts

@@ -0,0 +1,52 @@
+/**
+ * Drift guard: `KNOWN_ELEMENTS` in `known.ts` must match the `customElement`
+ * registrations under `src/components`. This is what would have caught
+ * `:md-card` — matched by the completion scanner but registered nowhere.
+ */
+
+import { readdirSync, readFileSync } from "fs";
+import { join } from "path";
+import { ELEMENT_NAMES } from "./known.js";
+import { renderReference } from "./reference.js";
+
+const COMPONENTS_DIR = join(process.cwd(), "src", "components");
+const CUSTOM_ELEMENT_RE = /customElement(?:<[^>]*>)?\(\s*["'](md-[\w-]+)["']/g;
+
+function sourceFiles(dir: string): string[] {
+  const files: string[] = [];
+  for (const entry of readdirSync(dir, { withFileTypes: true })) {
+    const full = join(dir, entry.name);
+    if (entry.isDirectory()) files.push(...sourceFiles(full));
+    else if (/\.tsx?$/.test(entry.name)) files.push(full);
+  }
+  return files;
+}
+
+function registeredElements(): Set<string> {
+  const names = new Set<string>();
+  for (const file of sourceFiles(COMPONENTS_DIR)) {
+    const source = readFileSync(file, "utf-8");
+    for (const match of source.matchAll(CUSTOM_ELEMENT_RE)) {
+      names.add(match[1]);
+    }
+  }
+  return names;
+}
+
+describe("known element catalog", () => {
+  test("matches the customElement registrations under src/components", () => {
+    const registered = [...registeredElements()].sort();
+    const known = [...ELEMENT_NAMES].sort();
+
+    expect(known).toEqual(registered);
+  });
+
+  test("docs/reference.md is up to date", () => {
+    const committed = readFileSync(
+      join(process.cwd(), "docs", "reference.md"),
+      "utf-8",
+    );
+
+    expect(committed).toBe(renderReference());
+  });
+});