feat(shipote): audit log persistente + HTTP gateway (fase S)

- Daemon escribe append-only a $XDG_STATE_HOME/shipote/audit.log además
  del tracing. Single-line: ts=<ms> uid=<peer> action=<verb> <detail>.
  Rotación simple a .log.1 al pasar 1 MiB.
- shipote-gateway: TCP listener 127.0.0.1:7378 default. POST /rpc traduce
  JSON ↔ postcard contra daemon socket. GET / health text. HTTP parser
  ad-hoc (~70 LOC), sin dep de hyper/axum. Sin auth — bind a localhost
  + SHIPOTE_TRUST_ANYONE=1 en prod.

E2E: curl --noproxy '*' POST /rpc → "Pong", Health JSON, Capabilities
JSON. Audit log persiste mutaciones con uid del peer.

85 tests pasan (features nuevos son binarios, no library mods).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Cargo.toml

@@ -109,6 +109,7 @@ members = [
     "crates/apps/brahman-demo",
     "crates/apps/shipote-daemon",
     "crates/apps/shipote-cli",
+    "crates/apps/shipote-gateway",
     "crates/apps/shipote-shell",
 ]