fix(opencode): resolve LSP dependencies from workspace root

[samiralibabic]

Issue for this PR

Closes #18694
Addresses #7690

Type of change

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

What does this PR do?

OpenCode can be launched from a monorepo root while the language project for a file lives in a child directory. Some built-in LSP servers already detect that child root, but still resolve project-local dependencies from the launch directory.

This changes built-in JS-family LSP dependency resolution to prefer the detected workspace root first, then fall back to the launch directory.

Changes:

• TypeScript resolves typescript/lib/tsserver.js from the detected root before the launch directory.
• ESLint resolves eslint from the detected root before the launch directory.
• Astro resolves TypeScript from the detected root before the launch directory.
• JS root markers now include package.json, tsconfig.json, and jsconfig.json, not only lockfiles.
• Missing dependency logs include root, launch directory, and worktree context.

This keeps existing fallback behavior while fixing child-package monorepo layouts.

How did you verify your code works?

• bun test test/lsp test/config/lsp.test.ts test/tool/lsp.test.ts
• bun typecheck
• pre-push typecheck passed: 14 successful, 14 total

Also tested locally with OpenCode launched from a repo root where the TypeScript package lives in a child directory.

Screenshots / recordings

N/A. This is not a UI change.

Checklist

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

[samiralibabic]

Updated the PR description to match the template.

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