Fase 5 — bus de agente (/run/agent.sock) + FIFO de control humano

- proto: tipos Command/Event con serde tag "t", Hello/Welcome handshake, RecipeInline
  reducida para COMPILE, Cap enum (Query/Compile/Inject/InjectReal/Init) y
  required_for() para gating por comando.
- bus: serve_agent_bus listens en UnixListener, autenticación SO_PEERCRED por
  conexión via nix::sys::socket::PeerCredentials, una conexión = reader thread +
  writer thread + bus-forwarder thread + worker spawn por COMPILE. Dispatch a
  hammer-build (Compile), find_by_hash+run_hydrate (Inject), stat (Query/file),
  store.find_by_hash (Query/artifact) y send_to_fifo (Init).
- events: EventBus in-process (Arc<Mutex<Vec<Sender>>>), suscripción por conexión
  y purga perezosa de subs muertos en publish.
- control: ensure_fifo (mkfifo idempotente, rechaza non-FIFO), run_reader (relog
  por línea, reabre al EOF), send_to_fifo (bloqueante si no hay reader).
- watcher: nuevo start_with_events que clona el EventBus; cada MutationEvent
  registrado se re-emite como Event::Modified a las conexiones abiertas.
- hammerd::main: orquesta FIFO + watcher + bus en threads; --no-watcher para
  dev sin CAP_SYS_ADMIN.
- hammer-cli: hammer ctl <line> [--fifo PATH] escribe al FIFO con error claro si
  no existe; reemplaza el stub "[fase 5 pendiente]".
- Tests:
  * 14 unit tests nuevos en hammerd (proto/bus/events/control).
  * 5 e2e en crates/hammerd/tests/bus_e2e.rs: handshake con peer creds, gating
    no_cap, Query/file, Modified fan-out vía bus, Init -> FIFO end-to-end.
- Docs: docs/10-roadmap.md actualizado con lo cerrado y lo pendiente (policy
  declarativa, CRASHED real con supervisor, log_tail en BuildFailed).

Cargo.lock

@@ -79,6 +79,12 @@ version = "0.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7c02d123df017efcdfbd739ef81735b36c5ba83ec3c59c80a9d7ecc718f92e50"
 
+[[package]]
+name = "autocfg"
+version = "1.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2032f911046de80f0a198e0901378627c33f59ea0ac00e363d481118bd70a53"
+
 [[package]]
 name = "base64"
 version = "0.22.1"
@@ -364,11 +370,14 @@ version = "0.0.1"
 dependencies = [
  "anyhow",
  "clap",
+ "hammer-build",
  "hammer-core",
  "hammer-journal",
  "hammer-overlay",
  "libc",
  "nix",
+ "serde",
+ "serde_json",
  "tempfile",
  "thiserror",
  "tracing",
@@ -477,6 +486,15 @@ version = "2.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6b947ae49db0d222b1dbc6b113ce7248a3fc3a6ca21b696717bfc000ba4484d8"
 
+[[package]]
+name = "memoffset"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "488016bfae457b036d996092f6cb448677611ce4449e970ceaf42695203f218a"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "nix"
 version = "0.30.1"
@@ -487,6 +505,7 @@ dependencies = [
  "cfg-if",
  "cfg_aliases",
  "libc",
+ "memoffset",
 ]
 
 [[package]]