feat(config): Add support for requires-arx in the .arxproject.toml

docs/getting-started.md

@@ -248,15 +248,27 @@ Example project manifest:
 [project]
 name = "geometry"
 version = "0.1.0"
+requires-arx = ">=1.0"
 
 [environment]
 kind = "conda"
 name = "geometry"
 
+[build-system]
+dependencies = [
+  "arxlang>=1.0",
+]
+
 [build]
 out_dir = "build"
 ```
 
+Use `[project].requires-arx` to declare the compatible Arx compiler versions for
+a project. The value uses the same version-specifier style as `requires-python`,
+for example `">=1.0,<2"`. `[build-system].dependencies` declares installable
+packages needed to build the project. If omitted, Arx defaults to `arxlang`; if
+`requires-arx` is present, the default build dependency uses that constraint.
+
 Use `__init__.x` as the package root. Arx uses `src/` as the default source root
 when `[build].src_dir` is omitted. Inside a nested module such as
 `geometry.shapes.area`, use relative `from` imports for nearby modules and

packages/arx/src/arx/schema/arxproject.json

@@ -72,6 +72,10 @@
           "type": "string",
           "minLength": 1
         },
+        "requires-arx": {
+          "type": "string",
+          "minLength": 1
+        },
         "edition": {
           "type": "string",
           "minLength": 1
@@ -147,15 +151,16 @@
         }
       }
     },
-    "toolchain": {
+    "build-system": {
       "type": "object",
       "additionalProperties": false,
       "properties": {
-        "compiler": {
-          "type": "string"
-        },
-        "linker": {
-          "type": "string"
+        "dependencies": {
+          "type": "array",
+          "items": {
+            "type": "string",
+            "minLength": 1
+          }
         }
       }
     },