Use mcdsl/terminal for all password prompts

Replace direct golang.org/x/term calls with mcdsl/terminal.ReadPassword
across mciasctl (6 sites), mciasgrpcctl (1 site), and mciasdb (1 site).
Aligns with the new CLI security standard in engineering-standards.md.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/modernc.org/libc/builtin64.go

@@ -22,3 +22,8 @@ func X__builtin_clzl(t *TLS, n ulong) int32 {
 func X__builtin_popcountl(t *TLS, x ulong) int32 {
 	return int32(mbits.OnesCount64(x))
 }
+
+// int __builtin_popcountll (unsigned long long)
+func X__builtin_popcountll(t *TLS, x uint64) int32 {
+	return int32(mbits.OnesCount64(x))
+}