feat: add production init wizard UX

packages/casan-devkit/tests/hybrid-install-tests.sh

@@ -80,11 +80,38 @@ assert registry["projects"] == []
 PY
 "$CASAN" version >/dev/null 2>&1 && pass "casan version works via launcher" || fail "casan version failed"
 python3 - "$CASAN_HOME/current/packages/casan-devkit/casan-init.py" <<'PY' \
-  && pass "client selector accepts menu numbers, aliases, repeats, and all" \
-  || fail "client selector normalization failed"
-import importlib.util,sys
+  && pass "init wizard resolves runtime and client choices safely" \
+  || fail "init wizard selection failed"
+import contextlib
+import importlib.util
+import io
+import sys
+
 spec=importlib.util.spec_from_file_location("casan_init",sys.argv[1])
 m=importlib.util.module_from_spec(spec); spec.loader.exec_module(m)
+
+# Explicit flags and existing project configuration never open a prompt.
+assert m.select_runtime_mode("vendored",None,True)=="vendored"
+assert m.select_runtime_mode(None,"vendored",True)=="vendored"
+assert m.select_runtime_mode(None,None,False)=="managed"
+
+# Interactive defaults, aliases, validation, and retry behavior.
+old_stdin=m.sys.stdin
+try:
+    m.sys.stdin=io.StringIO("\n")
+    with contextlib.redirect_stderr(io.StringIO()):
+        assert m.select_runtime_mode(None,None,True)=="managed"
+    m.sys.stdin=io.StringIO("9\n2\n")
+    with contextlib.redirect_stderr(io.StringIO()) as errors:
+        assert m.select_runtime_mode(None,None,True)=="vendored"
+    assert "Invalid selection" in errors.getvalue()
+    m.sys.stdin=io.StringIO("bogus\n3\n")
+    with contextlib.redirect_stderr(io.StringIO()) as errors:
+        assert m.select_clients(None,True)==["vscode-copilot"]
+    assert "Invalid selection" in errors.getvalue()
+finally:
+    m.sys.stdin=old_stdin
+
 assert m.select_clients(["1,3"],False)==["claude","vscode-copilot"]
 assert m.select_clients(["codex","copilot"],False)==["codex","vscode-copilot"]
 assert m.select_clients(["all"],False)==["claude","codex","vscode-copilot"]