docs: add companies frontmatter, schema, and rendering in badges & appendix pages

apps/docs/companies.ts

@@ -0,0 +1,36 @@
+/**
+ * The `companies:` frontmatter vocabulary, shared by its writer
+ * (`apps/cli/sync.ts`, from the local DuckDB company-frequency database), its
+ * schema (`blume.config.ts`) and its two readers: the company table under a
+ * problem page's badge row (`components/ProblemBadges.astro`) and the
+ * Companies section of the Appendix (`pages/appendix.astro`), where each
+ * company's card — anchored at `companyHref()` — lists the problems it asked.
+ * Plain data, no Astro imports: sync imports this file under Bun.
+ */
+
+/** The database's recency windows, most recent first; they nest, so a company is filed under the first it appears in. */
+export const RECENCY = ["Thirty Days", "Three Months", "Six Months"] as const;
+export type Recency = (typeof RECENCY)[number];
+
+/** Read under an "Asked within" heading (the company table) or as a row chip (the Appendix card). */
+export const RECENCY_LABEL: Record<Recency, string> = {
+  "Thirty Days": "30 days",
+  "Three Months": "3 months",
+  "Six Months": "6 months",
+};
+
+export interface Company {
+  name: string;
+  /** The most recent window the company asked the problem in. */
+  period: Recency;
+  /** 5–100, relative within the company and window: 100 is its most-asked problem there. */
+  frequency: number;
+}
+
+/** The company's card on the Appendix; `company-` keeps it clear of the tag cards' `#<slug>` ids. */
+export function companyHref(name: string): string {
+  return `/appendix#company-${name
+    .toLowerCase()
+    .replace(/[^a-z0-9]+/g, "-")
+    .replace(/^-|-$/g, "")}`;
+}