feat: add kitchen view command and parser skeleton (task 0003)

Cut the first complete thread through both layers with the smallest set
of node types.

@kitchen-md/core gains a pure, total `parse` returning a
`DocumentAST` of `{ frontmatter, blocks, diagnostics }`, built from a
minimal remark pipeline (remark-parse + remark-frontmatter) with an
internal translation layer to core's own types. This slice models
frontmatter passthrough, HeadingBlock, ParagraphBlock, and TextNode;
remark's mdast does not surface in the public API.

@kitchen-md/bin gains the `view` subcommand (commander) that reads a
file, calls `parse`, and passes the AST to a pure `render` that returns
an ANSI-styled string via chalk (auto-suppressed off a TTY). Frontmatter
prints as raw YAML followed by a separator, headings styled distinctly
by level, paragraphs as prose. A missing argument prints usage and a
missing/unreadable file a human-readable error, both exiting 1.

Richer blocks/inline plus raw fallbacks are task 0004; malformed
frontmatter diagnostics and the basic.md smoke test are task 0007.

packages/bin/src/integration_test.ts

@@ -1,5 +1,33 @@
-import { describe, test } from "bun:test";
+import { describe, expect, test } from "bun:test";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+import { runCli, stripAnsi } from "./test-support.ts";
+
+const CLI = `${import.meta.dir}/index.ts`;
 
 describe("cli — integration", () => {
-  test.todo("invokes core parser and produces output for a real fixture file");
+  test("invokes core parser and produces output for a real fixture file", async () => {
+    const dir = mkdtempSync(join(tmpdir(), "kitchen-md-"));
+    const file = join(dir, "recipe.md");
+    writeFileSync(
+      file,
+      "---\ntitle: Test Recipe\nservings: 2\n---\n\n# Heading One\n\nA plain paragraph of prose.\n",
+    );
+
+    try {
+      const { exitCode, stdout } = await runCli(["view", file], CLI);
+      const output = stripAnsi(stdout);
+
+      expect(exitCode).toBe(0);
+      expect(output).toContain("title: Test Recipe");
+      expect(output).toContain("servings: 2");
+      expect(output).toMatch(/─+/);
+      expect(output).toContain("Heading One");
+      expect(output).toContain("A plain paragraph of prose.");
+    } finally {
+      rmSync(dir, { recursive: true, force: true });
+    }
+  });
 });