fix(web): use release version for embedded UI

[bernhardberger]

Issue for this PR

Closes #29301
Refs #24286
Refs #18712

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Embedded release builds were reading the Web UI version from packages/app/package.json, while the CLI binary uses OPENCODE_VERSION / Script.version. Because package versions are synced later in the release flow, the embedded settings dialog could show the previous release.

This passes Script.version into the embedded Web UI build as VITE_OPENCODE_VERSION, uses it for platform.version, and keeps package.json as the local/dev fallback.

How did you verify your code works?

• VITE_OPENCODE_VERSION=9.9.9 bun run --cwd packages/app build
• confirmed the built app assets contain 9.9.9
• bun run --cwd packages/app typecheck
• OPENCODE_VERSION=9.9.9 bun ./packages/opencode/script/build.ts --single --skip-install
• confirmed dist/opencode-linux-x64/bin/opencode --version reports 9.9.9
• bun turbo typecheck passed locally: 19/19 tasks

Screenshots / recordings

N/A. This does not change layout or styling; it changes the release-time source for the version string shown in settings.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

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