fix: improve default fingerprint aggregation to reduce alert noise

[Royal-lobster]

Summary

• Normalize titles with the same built-in normalizers used for messages (UUIDs, hex addresses, timestamps, numbers) so dynamic values in titles don't split fingerprints
• Reduce default stackDepth from 3 to 1 so the same error from different callers (e.g. PrismaClientKnownRequestError via getUserPositions vs getUserTrades) groups into a single aggregation stream
• Users can restore previous behavior with fingerprint: { stackDepth: 3 }

Context

In production, a single root-cause error (missing DB table) was creating 6+ separate alert streams because each HTTP endpoint had a different caller in the stack trace. With these changes, they collapse into one stream with proper exponential ramp-up.

Test plan

• Added test: same error from different callers groups with default stackDepth
• Added test: dynamic hex addresses in titles produce same fingerprint
• All 135 existing tests pass

🤖 Generated with Claude Code

Closes #15

[gemini-code-assist]

Code Review

This pull request improves alert fingerprinting by normalizing titles to remove dynamic values and reducing the default stack depth from 3 to 1 to better group similar errors. A performance improvement was suggested to lazily compute the normalized title only when it is actually needed as a fallback for the error name.

[gemini-code-assist]

The normalizedTitle is computed eagerly using multiple regex replacements even when an error object is provided. Since error.name takes precedence in the errorName assignment, this computation is redundant when an error is present. It is more efficient to compute it only when needed.

Suggested change

	const normalizedTitle = normalizeMessage(title, config.normalizers)
	const normalizedMessage = normalizeMessage(message, config.normalizers)
	const stackKey = extractStackKey(error, config.stackDepth)
	const errorName = error?.name ?? title
	const errorName = error?.name ?? normalizedTitle
	const normalizedMessage = normalizeMessage(message, config.normalizers)
	const stackKey = extractStackKey(error, config.stackDepth)
	const errorName = error?.name ?? normalizeMessage(title, config.normalizers)