Initial commit: Naut-Torrent — from-scratch 10 GbE BitTorrent client

A maintainable, extensible BitTorrent client (C11, Linux/io_uring) targeting
10 GbE saturation. All torrent functionality is built from scratch; liburing
is the only linked third-party dependency on the data path.

Implements Phases 1-7 of the roadmap:
- core: page-aligned buffer pool, MPMC/Treiber queues, bitfields, worker pool
- crypto: SHA-1/256 (SHA-NI + scalar), Merkle (BEP-52), RC4 (MSE)
- bencode/metainfo: zero-copy parser, v1/v2/hybrid .torrent + magnet
- peer: sans-IO wire codec, MSE/PE handshake state machine, BEP-10, ut_metadata, PEX
- piece/storage: block-level multi-peer engine, rarest-first + endgame,
  per-file completion events + single-file relocate (move-as-you-finish)
- tracker/dht: HTTP + UDP (BEP-15) trackers, BEP-5 KRPC iterative lookup
- platform: io_uring reactor (SQPOLL, registered buffers, SEND_ZC)
- surface: versioned RPC, native plugin ABI, sandboxed Lua scripting, nautd/nautctl

Verified against libtorrent (single/multi/hybrid, MSE, magnet-via-DHT, swarm);
unit + interop tests green; ASan/UBSan/TSan clean. Scripting reference in
docs/scripting.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

include/naut/worker.h

@@ -0,0 +1,32 @@
+/* worker.h - bounded worker pool for hash/crypto jobs off the reactor path. */
+#ifndef NAUT_WORKER_H
+#define NAUT_WORKER_H
+
+#include "naut/common.h"
+
+typedef struct naut_worker_pool naut_worker_pool;
+typedef struct naut_job naut_job;
+typedef void (*naut_job_fn)(naut_job *job);
+
+struct naut_job {
+    naut_job_fn run;
+    void       *context;
+    naut_err    result;
+};
+
+/* Jobs are caller-owned and must remain alive until popped from completions.
+ * queue_capacity must be a power of two. cpu_base < 0 disables affinity. */
+naut_worker_pool *naut_worker_pool_create(uint32_t threads,
+                                          size_t queue_capacity,
+                                          int cpu_base);
+void naut_worker_pool_destroy(naut_worker_pool *pool);
+
+bool naut_worker_submit(naut_worker_pool *pool, naut_job *job);
+bool naut_worker_complete(naut_worker_pool *pool, naut_job **job);
+
+/* Readable when one or more jobs complete. The caller drains the eventfd and
+ * then pops completions. */
+int naut_worker_eventfd(const naut_worker_pool *pool);
+uint32_t naut_worker_threads(const naut_worker_pool *pool);
+
+#endif /* NAUT_WORKER_H */