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.ex

@@ -463,6 +463,7 @@ defmodule Un do
     {output, _exit} = System.cmd("curl", args, stderr_to_stdout: true)
 
     File.rm(tmp_file)
+    check_clock_drift(output)
     output
   end
 
@@ -497,6 +498,7 @@ defmodule Un do
     {output, _exit} = System.cmd("curl", args, stderr_to_stdout: true)
 
     File.rm(tmp_file)
+    check_clock_drift(output)
     output
   end
 
@@ -511,6 +513,7 @@ defmodule Un do
 
     {output, _exit} = System.cmd("curl", args, stderr_to_stdout: true)
 
+    check_clock_drift(output)
     output
   end
 
@@ -525,6 +528,7 @@ defmodule Un do
 
     {output, _exit} = System.cmd("curl", args, stderr_to_stdout: true)
 
+    check_clock_drift(output)
     output
   end
 
@@ -554,6 +558,26 @@ defmodule Un do
   defp get_opt([_arg | rest], long, short, default) do
     get_opt(rest, long, short, default)
   end
+
+  defp check_clock_drift(response) do
+    response_lower = String.downcase(response)
+
+    # Check if response contains "timestamp" and error indicators
+    has_timestamp = String.contains?(response_lower, "timestamp")
+    has_error = String.contains?(response_lower, "401") or
+                String.contains?(response_lower, "expired") or
+                String.contains?(response_lower, "invalid")
+
+    if has_timestamp and has_error do
+      IO.puts(:stderr, "#{@red}Error: Request timestamp expired (must be within 5 minutes of server time)#{@reset}")
+      IO.puts(:stderr, "#{@yellow}Your computer's clock may have drifted.")
+      IO.puts(:stderr, "Check your system time and sync with NTP if needed:")
+      IO.puts(:stderr, "  Linux:   sudo ntpdate -s time.nist.gov")
+      IO.puts(:stderr, "  macOS:   sudo sntp -sS time.apple.com")
+      IO.puts(:stderr, "  Windows: w32tm /resync#{@reset}")
+      System.halt(1)
+    end
+  end
 end
 
 Un.main(System.argv())