fix(hook): bound stdin read so a never-closing stdin can't wedge the hook

[Rome-1]

Problem

rafter hook pretool / hook posttool read stdin with a 5s timeout, but on Node that timeout only bounded output latency, not process exit. A piped stdin with no EOF stays in flowing mode and keeps the event loop alive — so after emitting its decision at 5s, the hook process hung indefinitely.

Reproduced (before fix):

$ sleep 30 | rafter hook pretool --format claude
{"hookSpecificOutput":{...,"permissionDecision":"allow",...}}   # printed at 5s
# ...then hangs forever — outer guard had to SIGKILL it (rc=124)

Any host that opens the hook's stdin but never writes/closes it wedges a zombie node per tool call. (Reported via hq-ryfyt from codegen_security_arena/crew/turing.)

Fix

• Node: on the timeout/end/error paths, remove listeners and process.stdin.pause() so the event loop drains and the process exits (~5s, fail-open). Verified: never-closing stdin now exits at ~5.5s default / ~0.9s with a 300ms override.
• Python: already exited (daemon reader thread doesn't block interpreter exit) — behavior unchanged; added a clarifying comment.
• Adds RAFTER_HOOK_STDIN_TIMEOUT_MS (ms, default 5000) as an operator safety valve and to keep tests fast. Both implementations parse it identically: finite and > 0, else fall back to default — so Infinity / nan / 0 / negative / garbage can never re-create the unbounded wait.

Security review (required gate)

Ran rafter-code-review (CWE Top-25 walk) on the diff. One finding, fixed in this PR:

Parity/fail-safe gap: Node rejects non-finite via Number.isFinite, but Python's float("inf") > 0 is True → join(timeout=inf) would reintroduce the exact hang. Guarded Python with math.isfinite to match Node.

Local secrets scan clean on all changed files. rafter run (remote SAST) not executed — no RAFTER_API_KEY in this environment; recommend CI runs it.

Tests

• Node (hook-stdin-timeout.test.ts): spawns the real hook with a never-closing stdin, asserts bounded exit + fail-open decision (pretool & posttool).
• Python (test_hook_stdin_timeout.py): asserts the bound returns promptly on a blocking stdin, and env parsing rejects non-finite / non-positive / garbage.
• All existing hook suites pass. (Note: hook-integration.test.ts > blocks rm -rf / fails on main too — pre-existing, unrelated to this diff; filed separately.)

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