refactor(engagement): Extract Test models into dojo/test/ module [3/10]

[valentijnscholten]

Stacked PRs

This is one of a stacked series that reorganizes dojo/ into self-contained dojo/{module}/ packages (matching the dojo/url/ reference). They are stacked — each PR is based on the previous one — so review and merge bottom-up in this order:

1. refactor(product_type): Extra ProductType models into dojo/product_type/ module [1/10] #14970 — product_type
2. refactor(test): Extract Test models into dojo/test/ module [2/10] #14971 — test
3. refactor(engagement): Extract Test models into dojo/test/ module [3/10] #14972 — engagement ◀ this PR
4. refactor(product): Extract Product module into dojo/product/ [4/10] #14973 — product
5. refactor(finding): Reorganize finding into self-contained dojo/finding/ package [5/10] #14974 — finding (+ CWE & BurpRawRequestResponse fold-in)
6. refactor(reorg): extract user + system_settings modules [6/10] #14981 — peripheral: user + system_settings
7. refactor(reorg): extract endpoint + tool_type/tool_config/tool_product modules [7/10] #14982 — peripheral: endpoint + tool_type/tool_config/tool_product
8. refactor(reorg): extract survey + benchmark modules [8/10] #14983 — peripheral: survey + benchmark
9. refactor(reorg): extract notes/note_type/file_uploads/reports/risk_acceptance [9/10] #14986 — peripheral: notes/note_type + file_uploads + reports + risk_acceptance
10. refactor(reorg): extract regulations/banner/announcement/development_environment/object [10/10] #14987 — peripheral: regulations + banner + announcement + development_environment + object

Merge #14970 first; each following branch is rebased onto the updated base and merged in turn. PRs 6–10 (draft, head branches on the DefectDojo upstream repo) continue the stack on top of #14974 — full implementation brief is the Phase 10 section in AGENTS.md.

Summary

Reorganizes the Engagement domain into a self-contained dojo/engagement/ package with ui/ and api/ subpackages, matching the dojo/url/ reference and the just-completed dojo/test/ module.

• Models — move Engagement, Engagement_Presets + admin into dojo/engagement/{models,admin}.py. Cross-module FKs use string references; ENGAGEMENT_STATUS_CHOICES single-sourced + re-exported. Engagement_Survey left in place.
• Services — extract the engagement copy workflow (clone + product grade recalc + notification) out of the copy_engagement view into an HTTP-free copy_engagement(engagement, user) service so UI and API can share it; view thinned to call it. Adds a unit test (the workflow was previously untested).
• Forms — move EngForm, DeleteEngagementForm, EngagementPresetsForm, DeleteEngagementPresetsForm, AddEngagementForm, ExistingEngagementForm into dojo/engagement/ui/forms.py.
• UI filters — move the EngagementDirect*, Engagement*, ProductEngagement(s)* and EngagementTest* filter classes into dojo/engagement/ui/filters.py (base classes like DojoFilter stay in dojo/filters.py).
• Views/URLs — move the engagement views and URL conf into dojo/engagement/ui/{views,urls}.py; update the dojo/urls.py include and the dojo/asset/urls.py consumer.
• API — move the engagement serializers into dojo/engagement/api/serializer.py (lazy imports for Note/File/TagList serializers to avoid a cycle), ApiEngagementFilter into dojo/engagement/api/filters.py, EngagementViewSet + EngagementPresetsViewset into dojo/engagement/api/views.py, and the DRF route registration into dojo/engagement/api/urls.py via add_engagement_urls(router). Routes and basenames (engagements/engagement, engagement_presets/engagement_presets) are preserved exactly.
• Backward-compat re-exports are kept where a symbol is still consumed by code remaining in the monolith (e.g. EngagementSerializer, the externally-used forms); re-exports that would create an import cycle (filters ↔ dojo.filters, viewsets/serializers ↔ dojo.api_v2) are dropped and the consumers point at the new path. No migration change.