add transport feature: meta-share transport-plugin contract, client, harness, focus replica, testkit

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "meta-feeder-sdk"
-version = "1.3.0"
+version = "1.4.0"
 edition = "2021"
 rust-version = "1.85"
 license = "MIT"
@@ -31,6 +31,14 @@ publish = false
 # and the libp2p wire. Keep heavy deps (librqbit, beetswap, cid, libp2p) OUT
 # of here so feeders that don't need them don't pay for them.
 
+[features]
+# The meta-share transport-plugin contract (`src/transport/`): the hull's
+# client, the plugins' axum harness, the focus replica, shared error/range
+# types. Off by default so feeders build exactly what they always did.
+transport = ["dep:cid", "dep:libc", "dep:tokio-util"]
+# Conformance checks any transport implementation must pass.
+testkit = ["transport"]
+
 [dependencies]
 # Async runtime + HTTP server (the serve_feeders harness)
 tokio = { version = "1.40", features = ["full"] }
@@ -58,6 +66,14 @@ regex = "1"
 # cache.rs. Pure-Rust single-process embedded store.
 redb = "2"
 
+# CID parsing for the transport contract only (`transport::cid`). Optional so
+# feeders don't pull it.
+cid = { version = "0.11", optional = true }
+# statvfs(2) for `transport::fsutil::available_bytes`.
+libc = { version = "0.2", optional = true }
+# `ReaderStream` for `transport::file`.
+tokio-util = { version = "0.7", features = ["io"], optional = true }
+
 [dev-dependencies]
 tempfile = "3"
 tokio = { version = "1.40", features = ["full", "test-util"] }