ci: [wip] Devcontainer-ready test images

[khvn26]

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3 Skipped Deployments

Project	Deployment	Review	Updated (UTC)
docs	Ignored		Jan 17, 2026 1:04am
flagsmith-frontend-preview	Ignored		Jan 17, 2026 1:04am
flagsmith-frontend-staging	Ignored		Jan 17, 2026 1:04am

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Docker builds report

Image	Build Status	Security report
ghcr.io/flagsmith/flagsmith-e2e:pr-6545	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-frontend:pr-6545	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-api-test:pr-6545	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-api:pr-6545	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith:pr-6545	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-private-cloud:pr-6545	Finished ✅	Results ✅