feat: [five-c] Create rules-based engine #409

[tdruez]

Issues

• Issue: five-c: Implement rules-based policy thresholds and alerting #408

Policy Rules Engine

• Rules engine that evaluates configurable compliance rules against products and records violations
• Five built-in rules covering usage policy errors/warnings, license policy errors/warnings, and license coverage gaps
• Per-dataspace configuration to enable/disable rules and override thresholds
• Automatic re-evaluation triggered when a product, its packages, or the dataspace configuration changes
• Background task support for evaluating one product or all products at once
• Webhook notifications on new violations detected or violations resolved
• Manual re-evaluation action available from the product admin and the compliance tab
• Compliance dashboard updated with a policy violations metric card and table column
• Per-product compliance tab showing active violations with rule details and detection date
• Product list filter to show only products with (or without) active policy violations
• REST API endpoint exposing active policy violations per product