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

Cut the first vertical slice through both layers: a runnable
`kitchen view <file>` that reads a Recipe File, parses it, and renders
it styled to the terminal.

@kitchen-md/core exposes a pure, total `parse(input): DocumentAST` built
on a minimal remark pipeline (parse + frontmatter) with a translation
layer to core's own AST types — frontmatter passthrough, HeadingBlock,
ParagraphBlock, and TextNode. remark types never leak into the public
API.

@kitchen-md/bin's `view` subcommand (commander) reads the file and hands
the DocumentAST to a pure `render(ast): string` (chalk, ANSI
auto-suppressed off a TTY). Fallible file I/O is modelled as a neverthrow
Result over a tagged-union CliError, matched at the boundary: stdout on
success, stderr and exit 1 on failure. The command functions sit beside
the import.meta.main-guarded CLI entry so they are testable in-process.

Tests follow ADR 0009's tiers — unit (parse, render), integration (the
view command's Result), and e2e (the binary as a subprocess) — with
coverage, a path-scoped test-report generator, and a prose fixture
rounding out the tooling. ADR 0008 records errors-as-values at the CLI
boundary; ADR 0009 records the testing tiers.

packages/core/src/parse_test.ts

@@ -0,0 +1,102 @@
+import { describe, expect, test } from "bun:test";
+import { parse } from "@kitchen-md/core";
+
+describe("parse", () => {
+  test("frontmatter passthrough — arbitrary fields become a plain object", () => {
+    const input = `---
+title: Buttered Toast
+servings: 2
+tags: [breakfast, simple]
+---
+
+# Buttered Toast
+`;
+
+    const result = parse(input);
+
+    expect(result.frontmatter).toEqual({
+      title: "Buttered Toast",
+      servings: 2,
+      tags: ["breakfast", "simple"],
+    });
+  });
+
+  test("frontmatter is an empty object when absent", () => {
+    const result = parse("# Just a heading");
+
+    expect(result.frontmatter).toEqual({});
+  });
+
+  test("frontmatter is an empty object when the block is empty", () => {
+    const input = `---
+---
+
+# Heading
+`;
+
+    const result = parse(input);
+
+    expect(result.frontmatter).toEqual({});
+  });
+
+  test("headings are modelled at every level 1–6 with TextNode children", () => {
+    const cases: [string, 1 | 2 | 3 | 4 | 5 | 6, string][] = [
+      ["# Level One", 1, "Level One"],
+      ["## Level Two", 2, "Level Two"],
+      ["### Level Three", 3, "Level Three"],
+      ["#### Level Four", 4, "Level Four"],
+      ["##### Level Five", 5, "Level Five"],
+      ["###### Level Six", 6, "Level Six"],
+    ];
+
+    for (const [markdown, level, text] of cases) {
+      const result = parse(markdown);
+
+      expect(result.blocks).toEqual([
+        {
+          type: "heading",
+          level,
+          children: [{ type: "text", value: text }],
+        },
+      ]);
+    }
+  });
+
+  test("a paragraph is a ParagraphBlock with TextNode content", () => {
+    const result = parse("Just some plain prose.");
+
+    expect(result.blocks).toEqual([
+      {
+        type: "paragraph",
+        children: [{ type: "text", value: "Just some plain prose." }],
+      },
+    ]);
+  });
+
+  test("blocks are flat and in document order — a heading is a sibling of the following paragraph", () => {
+    const input = `# Title
+
+A paragraph under it.
+`;
+
+    const result = parse(input);
+
+    expect(result.blocks).toEqual([
+      {
+        type: "heading",
+        level: 1,
+        children: [{ type: "text", value: "Title" }],
+      },
+      {
+        type: "paragraph",
+        children: [{ type: "text", value: "A paragraph under it." }],
+      },
+    ]);
+  });
+
+  test("diagnostics are empty in the normal case", () => {
+    const result = parse("# Ok");
+
+    expect(result.diagnostics).toEqual([]);
+  });
+});