Add v0.1 scaffold: tree-sitter-p8-cart grammar and Zed extension

The grammar parses the .p8 cartridge container ( header, version, and
the named __lua__/__gfx__/__gff__/__label__/__map__/__sfx__/__music__
sections, plus a fallback unknown_section ). The Zed language definition
hands the __lua__ body to Zed's built-in Lua via injections.scm, so
non-dialect Lua code highlights correctly today; PICO-8-specific syntax
(?, +=, !=, single-line if, etc.) will fall back to error highlighting
in those regions only — see README roadmap for the dialect grammar fork.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

package.json

@@ -0,0 +1,17 @@
+{
+  "name": "tree-sitter-p8-cart",
+  "version": "0.0.1",
+  "description": "tree-sitter grammar for the PICO-8 .p8 cartridge text format",
+  "main": "bindings/node",
+  "types": "bindings/node",
+  "keywords": [
+    "tree-sitter",
+    "parser",
+    "pico-8",
+    "pico8"
+  ],
+  "license": "0BSD",
+  "devDependencies": {
+    "tree-sitter-cli": "^0.24.7"
+  }
+}