Use the develop worker image automatically in local development

[mrubens]

Summary

• use the published roomote-worker:develop channel automatically for hosted providers in source development
• keep registry-qualified DOCKER_WORKER_IMAGE values as the explicit operator override
• preserve immutable RELEASE_VERSION-derived images for packaged deployments
• update cross-package regression coverage for provisioning and Modal configuration

Why

Source development previously fell back to roomote-worker:latest. The published development worker is released on the develop channel, while some hosted providers reject :latest outright. This caused automatic E2B and Daytona provisioning to fail unless developers manually configured an image in .env.local.

With this change, local development follows the published development channel automatically and no Settings field or persisted image override is needed.

Validation

• 2,912 tests across @roomote/types, @roomote/db, @roomote/compute-providers, and @roomote/web
• package lint and TypeScript checks
• pre-push lint:fast, check-types:fast, and Knip gates

[roomote-roomote]

No code issues found. See task

_{Reviewed f34d378}