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/package.json

@@ -11,6 +11,9 @@
     "build": "bun build --compile ./src/index.ts --outfile kitchen"
   },
   "dependencies": {
-    "@kitchen-md/core": "workspace:*"
+    "@kitchen-md/core": "workspace:*",
+    "chalk": "^5.6.2",
+    "commander": "^15.0.0",
+    "yaml": "^2.9.0"
   }
 }