fix(core): break filesystem search import cycle

[joe-ieta]

Issue for this PR

Closes #49685

Type of change

• Bug fix

What does this PR do?

packages/core/src/filesystem/search.ts imported the FileSystem self-namespace from ../filesystem to call Entry.make / Match.make, creating a runtime import cycle between filesystem.ts and filesystem/search.ts. In compiled builds that cycle can leave FileSystemSearch.node undefined while filesystem.ts builds its layer node, so booting a location crashes with TypeError: undefined is not an object (evaluating 'node.name') on the first prompt. Source mode happened to work because of ESM live bindings.

The fix imports Entry / Match directly from @opencode-ai/schema/filesystem and makes FileSystem a type-only import, removing the runtime cycle. Same values, no behavior change.

How did you verify your code works?

• bun run --cwd packages/core typecheck
• Compiled the server (bun run --cwd packages/opencode script/build.ts --single), ran serve, sent a prompt:
  • before: session.error with the node.name TypeError, assistant message never completes
  • after: assistant message completes with finish: "stop" and streams normally
• Re-ran the full flow against a real OpenAI-compatible provider

Screenshots / recordings

Not a UI change.

Checklist

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

[github-actions]

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Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

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[github-actions]

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[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍