feat: migrate to Effect 4 and Solid 2 RC

[joncrangle]

Summary

• Migrate Effect 3 to Effect 4 RC APIs and services.
• Migrate Solid 1 APIs to Solid 2 RC APIs without rendered effects in application code.
• Add the temporary OpenTUI 0.5.11 compatibility patch required by the current Solid 1-only renderer.
• Fix stale drive-selection errors and the live file-handle lifetime bug causing SystemError: Bad file descriptor.
• Add runtime, filesystem, and drive-selection regression coverage.

Validation

• bun install --frozen-lockfile
• just check
• just test — 149 passing
• just lint
• just build
• TUI smoke test completed without targeted runtime errors

Merge gates

This PR is intentionally a migration branch and should remain unmerged until:

1. Solid 2 is released out of RC.
2. Effect 4 is released out of RC.
3. OpenTUI officially supports Solid 2.x.
4. The OpenTUI compatibility patch can be removed and the application still passes a clean install, tests, build, and smoke test.

The OpenTUI packages are pinned to 0.5.11 while the patch is present to prevent version drift.

[joncrangle]

Merge-gate landing checklist

When Solid 2 / Effect 4 go stable and OpenTUI ships a Solid 2-native renderer, this is exactly what needs to change (verified 2026-09-20 — all three are still RC upstream, so nothing to do yet):

1. package.json — move solid-js off the exact RC pin to a stable range; move effect off the RC to stable; bump @opentui/solid + @opentui/core to the Solid 2-native release. Then bun install to regenerate bun.lock.
2. Delete patches/@opentui%2Fsolid@0.5.11.patch and remove the patchedDependencies entry. Each shim is documented inline in the patch (mergeProps/splitProps adapters, createRenderEffect adapter, onMount→onSettled swaps, ErrorBoundary→Errored, RendererContext change) — verify the native renderer covers each one.
3. Revisit src/__tests__/opentui_runtime.test.ts — it validates the patched behavior (settle-phase cleanup, render-phase Portal cleanup). The testRender import surface may move with the native renderer.
4. Bump @effect/language-service together with Effect, plus its tsconfig.json plugin entry — they are version-coupled.
5. No change needed: onSettled/Errored in src/ (index.tsx, Spinner.tsx, useAppLogic.ts) are native Solid 2 APIs (frozen at RC), and src/ has zero Solid 1 sites left.