Milestone 4: LAN discovery, trust gate, auto-sync, rate limits, events

mDNS-style LAN discovery (iroh MdnsDiscovery, discovery flag, default
on) feeds a presence tracker; trusted peers that appear trigger fetches
of every incomplete pin, and Pin itself now fetches from present
trusted peers. Serving is our own ProtocolHandler: trusted NodeIds get
the full store, everyone else a filtered view limited to open_lan pins
and ticket-exported hashes (plus hashseq children) that answers "not
found" for the rest. Ticket export records standing serve-consent for
that hash; trust changes take effect on new connections. ShapedStore
implements the full iroh-blobs Store trait to charge provider reads to
an upload token bucket and downloader writes to a download bucket;
upload cap 0 closes incoming connections at accept. Subscribe now
streams transfer_progress both ways, peer_joined, and pin_complete.

Tests: forged-ticket trust gating (denied untrusted, served after
trust), 256 KiB/s upload cap enforced by wall clock, event stream
during a transfer, and real-mdns auto-sync between two daemons
(skips where multicast is unavailable).

Dependencies: n0-future, async-channel, futures-lite, bytes — all
already in the tree via iroh; needed directly to name types in
iroh-blobs trait signatures and channels. iroh feature
discovery-local-network for MdnsDiscovery.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

varde-daemon/tests/support/mod.rs

@@ -47,9 +47,15 @@ pub fn spawn_daemon() -> DaemonProc {
 
 /// Spawn the daemon against an existing directory (for restart tests).
 pub fn spawn_daemon_at(dir: &Path) -> DaemonProc {
+    spawn_daemon_with_env(dir, &[])
+}
+
+/// Spawn the daemon with extra environment variables (config overrides).
+pub fn spawn_daemon_with_env(dir: &Path, envs: &[(&str, &str)]) -> DaemonProc {
     let socket = dir.join("varde.sock");
     let store = dir.join("store");
-    let child = Command::new(env!("CARGO_BIN_EXE_varde-daemon"))
+    let mut command = Command::new(env!("CARGO_BIN_EXE_varde-daemon"));
+    command
         .arg("--user")
         .arg("--socket")
         .arg(&socket)
@@ -57,9 +63,11 @@ pub fn spawn_daemon_at(dir: &Path) -> DaemonProc {
         .arg(&store)
         // Isolate from any config file on the developer's machine.
         .env("VARDE_CONFIG", dir.join("no-config.toml"))
-        .env("VARDE_DISCOVERY", "false")
-        .spawn()
-        .expect("spawning varde-daemon");
+        .env("VARDE_DISCOVERY", "false");
+    for (key, value) in envs {
+        command.env(key, value);
+    }
+    let child = command.spawn().expect("spawning varde-daemon");
     // An explicitly named config must exist for the daemon to start.
     std::fs::write(dir.join("no-config.toml"), "").expect("writing empty config");
 
@@ -129,6 +137,13 @@ impl Client {
         serde_json::from_str(&reply).expect("parsing reply envelope")
     }
 
+    /// Bound how long reads may block (applies to the shared socket).
+    pub fn set_read_timeout(&mut self, timeout: Duration) {
+        self.writer
+            .set_read_timeout(Some(timeout))
+            .expect("setting read timeout");
+    }
+
     /// Read one line of the event stream (after Subscribe).
     pub fn read_event_line(&mut self) -> Option<String> {
         let mut line = String::new();