fix(stream-install)!: stream archive payloads as raw frames

Streamed installs were sending FileChunk payloads through the shared JSON
Message impl. serde_json serializes bytes as arrays of integers, which
bloats wire traffic and burns CPU on large archives. Replace
StreamInstallFrame encoding with tagged frames: JSON control frames keep
their shape under tag 0, while file chunks carry raw bytes under tag 1.

The stream install metadata now carries unpacked archive size and mandatory
CRC32. The CLI unrar provider validates CRCs up front, runs one
archive-wide unrar p stream, splits stdout by listed file sizes, and
refuses trailing or missing bytes. That avoids solid archive
re-decompression and sidesteps unrar wildcard masks for path arguments.

Receivers now sample existing download progress events for streamed
installs, report staging-relative chunk paths, and retry trusted peers with
a fresh streamed-install transaction after a failed attempt. The current
protocol policy does not preserve compatibility with older stream-install
builds.

Test Plan:
- just fmt
- just test
- just clippy
- git diff --check
- git diff --cached --check

BREAKING CHANGE: StreamInstallFrame now uses tagged frames with raw chunk
payloads and requires current peers on both sides of streamed installs.

Refs: NEXT_STEPS_CLAUDES_REVIEW.md

crates/lanspread-proto/tests/stream_install_frame.rs

@@ -0,0 +1,42 @@
+use bytes::Bytes;
+use lanspread_proto::{Message, StreamInstallFrame};
+
+#[test]
+fn file_chunks_encode_raw_bytes() {
+    let bytes = Bytes::from_static(&[0, 1, 2, 255]);
+    let encoded = StreamInstallFrame::FileChunk {
+        bytes: bytes.clone(),
+    }
+    .encode();
+
+    assert_eq!(&encoded[..], &[1, 0, 1, 2, 255]);
+    assert_eq!(
+        StreamInstallFrame::decode(encoded),
+        StreamInstallFrame::FileChunk { bytes }
+    );
+}
+
+#[test]
+fn control_frames_are_tagged_json() {
+    let frame = StreamInstallFrame::FileBegin {
+        relative_path: "bin/game.exe".to_string(),
+        size: 42,
+        crc32: 0x38B4_88A7,
+    };
+    let encoded = frame.encode();
+
+    assert_eq!(encoded[0], 0);
+    assert_eq!(StreamInstallFrame::decode(encoded), frame);
+}
+
+#[test]
+fn empty_frames_decode_as_errors() {
+    match StreamInstallFrame::decode(Bytes::new()) {
+        StreamInstallFrame::Error { message } => {
+            assert!(message.contains("empty"));
+        }
+        other => {
+            panic!("expected error frame, got {other:?}");
+        }
+    }
+}