fix(analytics): add try/catch in middleware finish handler

[PierreBrisorgueil]

Context

The analytics auto-capture middleware registers a res.on('finish') handler that calls AnalyticsService.track(). If track() throws, it becomes an unhandled error in the finish event. Risk is low (track guards with if (!client) return) but not zero.

What

• Wrap the res.on('finish') body in try/catch (same pattern as audit middleware .catch(() => {}))
• Add unit test for the error path

Acceptance

• Analytics middleware finish handler catches exceptions
• Test verifies no unhandled error when track() throws