chore: Archive zyn_parser, superseded by zyn_peg

- Move crates/zyn_parser to archive/zyn_parser
- Remove zyn_parser from workspace members in Cargo.toml
- Add archive/README.md explaining the archive
- Add .vscode/settings.json to associate .zyn files with pest syntax

The old hand-written zyn_parser has been superseded by zyn_peg,
which uses a PEG grammar approach with JSON semantic actions.
The new approach is more maintainable and flexible.

Author: darmie

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "files.associations": {
+        "*.zyn": "pest"
+    }
+}

Cargo.toml

@@ -1,6 +1,6 @@
 [workspace]
 resolver = "2"
-members = ["crates/typed_ast", "crates/compiler", "crates/whirlwind_adapter", "crates/zyntax_cli", "crates/runtime", "crates/zyntax_plugin_macros", "crates/zyn_parser", "crates/zyn_peg"]
+members = ["crates/typed_ast", "crates/compiler", "crates/whirlwind_adapter", "crates/zyntax_cli", "crates/runtime", "crates/zyntax_plugin_macros", "crates/zyn_peg"]
 
 
 [workspace.dependencies]

archive/README.md

@@ -0,0 +1,18 @@
+# Archive
+
+This directory contains deprecated/archived code that is kept for reference but is no longer part of the active codebase.
+
+## Contents
+
+### zyn_parser
+
+**Archived:** November 2024
+
+The original hand-written parser for the Zyn language. This has been superseded by `zyn_peg`, which uses a PEG grammar approach with JSON semantic actions to generate TypedAST directly at parse time.
+
+The new approach (`crates/zyn_peg`) is:
+- More maintainable (grammar + actions in a single `.zyn` file)
+- More flexible (easy to add new language frontends)
+- Better documented (see `book/` directory)
+
+If you need to reference the old implementation, it's preserved here.