Add clock drift error messages to remaining 18 implementations

When timestamp auth fails (401 with timestamp in error), show helpful message:
- Error: Request timestamp expired (must be within 5 minutes of server time)
- Your computer's clock may have drifted.
- NTP sync commands for Linux/macOS/Windows

Updated: Un.cs, Un.java, un.clj, un.cob, un.erl, un.ex, un.f90, un.forth,
un.fs, un.hs, un.lisp, un.m, un.ml, un.pro, un.r, un.raku, un.scm, un.zig

All 42 implementations now have clock drift detection.

Un.java

@@ -555,6 +555,18 @@ public class Un {
         int status = conn.getResponseCode();
         if (status < 200 || status >= 300) {
             String error = readStream(conn.getErrorStream());
+
+            // Check for clock drift errors
+            if (error.contains("timestamp") && (status == 401 || error.toLowerCase().contains("expired") || error.toLowerCase().contains("invalid"))) {
+                System.err.println(RED + "Error: Request timestamp expired (must be within 5 minutes of server time)" + RESET);
+                System.err.println(YELLOW + "Your computer's clock may have drifted." + RESET);
+                System.err.println("Check your system time and sync with NTP if needed:");
+                System.err.println("  Linux:   sudo ntpdate -s time.nist.gov");
+                System.err.println("  macOS:   sudo sntp -sS time.apple.com");
+                System.err.println("  Windows: w32tm /resync");
+                System.exit(1);
+            }
+
             throw new Exception("HTTP " + status + " - " + error);
         }