feat: enable sandbox environments by default and remove related featu…

[thesujai]

…re flag

Summary

Closes #

Changes

How was this tested?

Checklist

• I have read the contributing guidelines
• pnpm build, pnpm test, pnpm typecheck, pnpm lint:ci, and pnpm format:check pass locally
• Tests added/updated where it makes sense
• No hand-edits to generated code (packages/trueforge-sdk, python/trueforge_sdk, .github/fern/openapi/openapi.json, docs/openapi.json) — fork PRs omit SDK regen; maintainers regenerate after merge
• Docs / .env.example updated if configuration or behavior changed

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Note

Low Risk
Frontend-only graduation of an existing UI path; no auth or data-model changes, though embedders can no longer disable environments via the removed sandboxEnvironments server prop.

Overview
Removes the sandbox environments frontend feature flag so the environments UI is always on in dev, Docker builds, and the default Harness adapter.

Build & host: Drops VITE_SANDBOX_ENVIRONMENTS_ENABLED from the Dockerfile frontend stage and from packages/frontend (App.tsx no longer passes sandboxEnvironments on the TrueForgeUI server config). README no longer documents opting in via that env var.

@truefoundry/trueforge-ui: Deletes the sandboxEnvironments?: boolean option from TrueForgeBuiltInServerConfig and createTrueForgeAgentUIServer; the adapter always registers createSandboxEnvironmentServer. Draft composer and agent runtime config no longer hide the Environment tab or environment selector when a sandbox-environment server port was absent—they always render those controls (still subject to sandbox enablement / availability). Tests that asserted flag-off behavior are removed or updated.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 4e5630f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@truefoundry/trueforge	Patch
@truefoundry/trueforge-ui	Patch

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[chiragjn]

Blind approve, get reviewed with @harshil-2096