Milestone 2: persistent blob store, add/materialize/gc

iroh-blobs 0.35 fs store under <store_dir>/blobs. Add imports files or
whole directory trees (as Collections, deterministic order), Materialize
exports them with a real FICLONE reflink attempt and streaming-copy
fallback, Gc is an explicit mark-and-sweep rooted at the pins. Pins,
trusted peers and hash formats persist in meta.json (atomic writes).
Store reads run on a LocalPool because iroh-blobs entry readers are not
Send. Integration tests drive the real daemon binary: directory round
trip byte-identical, gc keeps pinned/drops unpinned, reflink verified on
the repo's own filesystem (XFS), plus a 32-case proptest round trip.

Dependencies: iroh-blobs =0.35.0 (the store itself; pinned per spec),
iroh-io (AsyncSliceReader traits to read store entries), reflink-copy
(FICLONE with copy fallback, per spec), proptest (dev-only, round-trip
property test).

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

varde-daemon/src/main.rs

@@ -82,15 +82,16 @@ fn main() -> Result<()> {
 
 async fn run(config: Config) -> Result<()> {
     let socket_path = config.socket_path.clone();
+    let daemon = Arc::new(daemon::Daemon::open(config).await?);
     let listener = server::bind_socket(&socket_path)?;
-    let daemon = Arc::new(daemon::Daemon::new(config));
 
     let result = tokio::select! {
-        r = server::serve(listener, daemon) => r,
+        r = server::serve(listener, daemon.clone()) => r,
         r = shutdown_signal() => r.map(|signal| info!(signal, "shutting down")),
     };
 
-    // Best-effort cleanup so the next start doesn't find a stale socket.
+    // Flush the store and remove the socket so the next start is clean.
+    daemon.store().shutdown().await;
     let _ = std::fs::remove_file(&socket_path);
     result
 }