[PM-40160] SecurityTasksNotification copy update

[jengstrom-bw]

🎟️ Tracking

Jira

📔 Objective

Adds new email templates SecurityTasksNotificationV2 that update the copy of SecurityTasksNotification. These templates are behind the VFO1Foundation feature flag

[github-actions]

ℹ️ Limited Platform familiarity

This PR touches a platform-community area. The Platform team owns this code but does not actively develop it, so a Platform review here may be less authoritative than usual.

[github-actions]

🤖 Bitwarden Claude Code Review

Overall Assessment: APPROVE

This PR adds SecurityTasksNotificationV2 email templates (HTML and text) with updated copy, gated behind the existing VFO1Foundation feature flag. The SendBulkSecurityTaskNotificationsAsync signature gains a backward-compatible useV2Template = false parameter, propagated consistently across IMailService, HandlebarsMailService, and NoopMailService, with the flag resolved via IFeatureService in CreateManyTaskNotificationsCommand. Unit tests cover both the flag-enabled and flag-disabled paths.

Code Review Details

No blocking findings.

• New .hbs templates are picked up by the **\*.hbs embedded-resource glob in Core.csproj, and AddMessageContentAsync resolves both .html and .text variants from the single template name, so the V2 templates load correctly.
• The added parameter defaults to false, preserving backward compatibility for existing callers.
• Feature-flag wiring and DI registration follow existing conventions; tests use SutProvider/BitAutoData per repo standards.

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 62.29%. Comparing base (5e3ce1c) to head (b2217dc).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Core/Platform/Mail/HandlebarsMailService.cs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7997      +/-   ##
==========================================
+ Coverage   62.15%   62.29%   +0.13%     
==========================================
  Files        2284     2287       +3     
  Lines       99649    99667      +18     
  Branches     9012     9005       -7     
==========================================
+ Hits        61934    62083     +149     
+ Misses      35538    35413     -125     
+ Partials     2177     2171       -6     

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