fix: deadlock in std_log_impl macro on write failure

[kpraneet]

The std_log_impl macro, deadlocks when a write operation fails. This occurs because the stream lock is still held when fallback_on_error attempts to write the error message.

The fix modifies the macro to properly scope the stream lock:

• Ensure lock is released after write attempts by using explicit scope
• Handle lock release before error propagation via result?
• Maintain same behavior for both meta-logging and standard logging paths

Before:

write!(self.stream.lock(), "{}", msg)?;
// Lock held during error propagation

After:

let result = {
    let mut writer = self.stream.lock();
    write!(writer, "{}", msg)
}; // Lock released here
result?; // Error propagation after lock release

This prevents the deadlock by ensuring the stream lock is always released before any error handling occurs through fallback_on_error.

Fixes #150

Validation:

• Verified fix using the sample test application from the issue
• Meets contribution guidelines and coding standards
• All tests pass successfully