metrics: use mitigated_date for closed findings

[valentijnscholten]

Fixes using Cursor AI.

Fix: Closed Findings Metrics Use Mitigated Date Instead of Discovery Date

Fixes #9735

Problem

The "Closed Findings" metric in the Metrics dashboard incorrectly uses the finding's discovery date (date field) instead of its mitigated date (mitigated field) for filtering and grouping. This causes inaccurate reporting when filtering by date ranges that don't include the original discovery date.

Solution

Updated metrics calculation logic to use the mitigated date field for closed findings:

Impact

Closed findings metrics now accurately reflect when findings were actually closed/mitigated, rather than when they were discovered, providing more accurate reporting for security teams.

[dryrunsecurity]

🔴 Risk threshold exceeded.

This pull request modifies two template files (dojo/templates/dojo/engagements_all.html and dojo/templates/dojo/product.html) that were flagged as sensitive codepath edits; review is recommended and sensitive paths/allowed authors can be configured in .dryrunsecurity.yaml.

🔴 Configured Codepaths Edit in dojo/templates/dojo/engagements_all.html

Vulnerability	Configured Codepaths Edit
Description	Sensitive edits detected for this file. Sensitive file paths and allowed authors can be configured in .dryrunsecurity.yaml.

🔴 Configured Codepaths Edit in dojo/templates/dojo/product.html

Vulnerability	Configured Codepaths Edit
Description	Sensitive edits detected for this file. Sensitive file paths and allowed authors can be configured in .dryrunsecurity.yaml.

We've notified @mtesauro.

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All finding details can be found in the DryRun Security Dashboard.

[mtesauro]

Approved