Allow creating issues from structured logs (especially error-level logs from log drains)

### Problem Statement

Structured logs from log drains (e.g., Vercel) arrive in Sentry with full context (message, severity, timestamp, trace ID) but there's no way to promote them into issues.

This is a significant gap for platform-level errors like Vercel serverless timeouts ("Task timed out after 800 seconds"). The platform kills the process before the SDK can capture anything, so the only record is the log from the drain. That log has everything needed to create an issue, but it just sits in the Logs explorer with no way to act on it.

Log-based metric alerts partially address this, but the Slack notifications they produce are generic.

### Solution Brainstorm

Ability to create issues from such logs, maybe something similar to Performance and Replay issues. An automatic issue creation would be very helpful, especially for log drain users who rely on platform logs for errors the SDK physically cannot capture.

### Additional Context

Customer case: https://sentry.zendesk.com/agent/tickets/178423

### Priority

_{React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding `+1` or `me too`, to help us triage it.}

No files, tests, or entry points are identified in the issue. Start by tracing the Logs explorer and existing issue-creation flows, then define the supported log fields, creation behavior, and tests needed to show that a structured log can become an issue.

Written by the indexing model from the issue text.