feat(shipote): throughput + stats persistente + auth peer (fase P)

- FlowMeter (atomic u64 + rolling window 32 samples) en cada FlowChannel.
  flow_throughput() → (socket, bytes_total, bytes_per_sec). CLI:
  shipote flow throughput. Idle threshold 5s = rate 0.0.
- Snapshot v4 con stats_history persistente por workspace (cap 16).
  PersistedStats separado para evitar Instant. Restore hidrata el VecDeque
  con source="persisted".
- Auth SO_PEERCRED: daemon rechaza peers con uid distinto al propio.
  SHIPOTE_TRUST_ANYONE=1 = escape hatch documentado.

84 tests pasan (ente-incarnate 16, nouser-core 27, shipote-card 8,
shipote-core 25, shipote-discern 5, yahweh-provider-fs 3).

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

crates/modules/shipote/shipote-protocol/src/lib.rs

@@ -134,6 +134,9 @@ pub enum Request {
     /// Listar pipelines activos con sus flow channels (data plane).
     FlowList,
 
+    /// Throughput por flow socket: bytes_total + bytes_per_sec.
+    FlowThroughput,
+
     /// Cerrar el data plane de un pipeline (drop sockets + canales).
     FlowDrop { pipeline: Ulid },
 }
@@ -233,6 +236,10 @@ pub enum Response {
         items: Vec<FlowInfo>,
     },
 
+    FlowThroughput {
+        items: Vec<FlowThroughputInfo>,
+    },
+
     FlowDropped {
         pipeline: Ulid,
         existed: bool,
@@ -270,6 +277,13 @@ fn default_cpu_cores() -> u32 {
     1
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct FlowThroughputInfo {
+    pub socket: PathBuf,
+    pub bytes_total: u64,
+    pub bytes_per_sec: f64,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct FlowInfo {
     pub pipeline: Ulid,