fix(claude-code-adapter): send the prompt over stdin, not argv; retry temp cleanup

[rembradtech]

Summary

Two real, reproducible failures reviewing PRs on Windows tonight, hit on every single review attempted, regardless of file content:

1. spawn ENAMETOOLONG — runClaude built args = ["-p", prompt], passing the whole prompt (system + conversation, and for a file review, the file's own content) as one CLI argument. Windows' ~32K total command-line length is exceeded by a real file's content plus review instructions regardless of the file's own size — even a single, unremarkable source file failed this way. No batching or token-budget config can fix this: it's the argv itself that's too long, independent of how many files or tokens are involved.

   Fix: claude -p (bare, no literal argument) reads its prompt from stdin instead — verified live. runLocalCli gained a stdin option (written to the child before closing it; empty otherwise, so existing callers that don't pass it see no behavior change), and runClaude/claudeCode now send the prompt that way.

2. EBUSY: resource busy or locked — cleanup()'s rmSync(tempRoot, ...) crashed the whole run uncaught, on every single invocation observed. A spawned child's handle on a file under tempRoot can linger briefly past close on Windows, racing the parent's cleanup rmSync. fs.rmSync's own maxRetries/retryDelay options exist for exactly this documented behavior.

Test plan

• npm run typecheck
• New tests: the stdin option writes content to the child before it closes; omitting it still closes stdin empty (no behavior change for existing callers)
• Full suite: 222/309 passing after this change vs. 220/307 before — same 86 pre-existing failures either way (Windows path-separator assertions unrelated to this PR, confirmed via git stash against this same branch point), plus the 2 new tests above, both passing
• Live: re-ran a real PR review that failed with ENAMETOOLONG on every attempt before this fix (AgentsKit-io/agentskit-os#6233) — completed with neither ENAMETOOLONG nor EBUSY after this fix

https://claude.ai/code/session_0137fexM8CEcWe2N2Y7igkUY