docs: clarify Claro v1 status and validation

tools/validate_rc3.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+import subprocess
+import sys
+from pathlib import Path
+
+root = Path(__file__).resolve().parents[1]
+exe = root / ("claro.exe" if sys.platform.startswith("win") else "claro")
+
+def run(args, expect=0, input_text=None):
+    p = subprocess.run(args, cwd=root, input=input_text, text=True,
+                       stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    if p.returncode != expect:
+        print("FAILED:", " ".join(map(str,args)))
+        print(p.stdout)
+        print(p.stderr)
+        sys.exit(1)
+    return p.stdout + p.stderr
+
+run([str(exe), "--version"])
+run([str(exe), "test"])
+run([str(exe), "check", "lessons/01_hello.claro"])
+run([str(exe), "check", "lessons/08_functions.claro"])
+run([str(exe), "check", "tests/checker_fixtures/bad_unknown_command.claro"], expect=1)
+run([str(exe), "check", "tests/checker_fixtures/bad_typo_command.claro"], expect=1)
+print("RC3 validation passed")