Keep ntfy exception alerts readable with structured message trimming and stacktrace attachments

This release improves how exception notifications are formatted for ntfy, especially when stacktraces grow large enough to trigger ntfy's automatic attachment.txt behavior.

The logger now builds exception notifications through a structured NtfyMessageBody, which keeps the visible notification under ntfy’s 4096-byte message limit when possible. If trimming is required, the phone-friendly message keeps the most useful debugging information visible: the log message, inner-most exception summary, runtime context, and a capped stacktrace excerpt.

When the full exception output is too large for the visible notification, the complete stacktrace is uploaded as stacktrace.txt while the shortened Markdown message remains directly readable in the notification.

Also included:

• Inner-most exception rendering for compact alert messages
• Stacktrace excerpts limited to the last 10 frames
• Local attachment publishing support in NtfyClient
• Additional tests for message budgeting, attachment publishing, runtime context, and logger behavior