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/tests/support/mod.rs

@@ -1,6 +1,10 @@
 //! Shared helpers for integration tests: spawn the real daemon binary on
 //! ephemeral paths and speak the JSON-lines protocol to it.
 
+// Each test binary compiles its own copy of this module and none of them
+// uses every helper.
+#![allow(dead_code)]
+
 use std::io::{BufRead, BufReader, Write};
 use std::os::unix::net::UnixStream;
 use std::path::{Path, PathBuf};
@@ -118,9 +122,6 @@ impl Client {
     }
 
     /// Read one line of the event stream (after Subscribe).
-    // Each test binary compiles its own copy of this module; not every
-    // binary uses every helper.
-    #[allow(dead_code)]
     pub fn read_event_line(&mut self) -> Option<String> {
         let mut line = String::new();
         match self.reader.read_line(&mut line) {