Customizable Email Subjects for Workflow Notifications

### Problem Statement

Users need the ability to quickly identify and triage workflow notifications—especially those for "Resolved" and "Regression" statuses—directly from their inbox. The current email subjects do not indicate these statuses clearly, making it challenging to scan or automate email routing rules.

### Solution Brainstorm

Add a configuration option in the settings that allows customization of email subjects for different workflow statuses (e.g., placeholders like
STATUS, ISSUE, etc.). By default, the system could prepend the relevant status keyword (e.g., “[REGRESSION]” or “[RESOLVED]”) to the existing subject line.

### Product Area

Settings - General

No file, test, or entry point is named. Start by tracing the General settings flow for workflow notification emails and how subjects are generated; clarify supported statuses, placeholders, and default prefixes before implementation. Done means configurable subjects work for the requested statuses and their behavior is covered by tests.

Written by the indexing model from the issue text.