fix(core): break filesystem cycle in compiled prompts

[kernel-oops]

Issue for this PR

Related to #44946; no separate issue. This complements that Bun upgrade rather than duplicating its runtime pin change. The upgrade is useful for fixes such as oven-sh/bun#35356 (GC timer CPU usage), but compiled prompt preparation also needs checking.

Type of change

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

What does this PR do?

Remove the runtime import from filesystem search back to the filesystem service. Schema constructors now come directly from the schema package; service input imports remain type-only.

The service depends on the search node. With Bun 1.4.2, the compiled cycle can capture an undefined dependency: health passes, but the first prompt fails in SystemPrompt.environment with TypeError: undefined is not an object (evaluating 'a.name'), before any provider request.

Add an isolated compiled regression and a path-filtered Linux CI job using Bun 1.4.2. The runner exercises authenticated session creation, a streamed request for the actual read tool, completion, persisted tool output and a second turn. All provider responses are deterministic and local.

How did you verify your code works?

Fresh upstream dev at 193de13a88d62a6409c6d385831180f1def527dc, Linux x64/glibc, Bun 1.4.2, native minified/split builds with embedded web UI:

• Before: health passes; first prompt fails with the error above; zero provider requests.
• After: compiled regression passes; exactly three provider requests. The embedded runtime is checked by the runner.
• Frozen-lockfile installation; no lockfile changes.
• Core filesystem/location/read tests: 46 pass, also 46 pass with FFF disabled.
• Isolated processor/permission/config/storage tests: 345 pass, 3 platform skips. An initial run inherited local configuration and failed; the clean-environment rerun passed.
• Core and OpenCode typechecks, formatting, Python syntax, workflow YAML and inline shell checks pass.

Draft pending upstream CI/review and broader platform/soak coverage. Windows runner support, other binary targets, real providers and CPU benchmarks were not tested here.

Screenshots / recordings

Not applicable.

Checklist

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

Fixes #48372

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