test(peer-cli): add large exact-transfer coverage

Add deeper peer CLI coverage for file-transfer integrity and multi-peer
chunking. The alpha fixture now carries a real renamed RAR archive larger
than 100 MB for alienswarm, which gives the chunk planner enough work to
split a single game archive across multiple peers.

Expose completed chunk source details as a peer event and have the CLI print
that event as JSONL. This keeps transfer behavior in lanspread-peer while the
CLI remains a harness that reports what the peer runtime did. The Tauri shell
logs the event at debug level so the shared PeerEvent enum stays exhaustive.

Document the new S13/S14 scenarios and record the manual run evidence,
including SHA-256 manifests and the per-peer byte split for the large archive.

Test Plan:
- just fmt
- just test
- just peer-cli-build
- just clippy
- just peer-cli-image
- unrar t -idq crates/lanspread-peer-cli/fixtures/fixture-alpha/alienswarm/alienswarm.eti
- Manual peer CLI: bravo -> deep-small-client bfbc2 download with matching SHA-256 manifests
- Manual peer CLI: alpha -> deep-stage-b alienswarm download with matching SHA-256 manifests
- Manual peer CLI: alpha + deep-stage-b -> deep-stage-c alienswarm download with chunk events from both peers and matching SHA-256 manifests

Refs: PEER_CLI_SCENARIOS.md S13 S14

crates/lanspread-tauri-deno-ts/src-tauri/src/lib.rs

@@ -795,6 +795,18 @@ async fn handle_peer_event(app_handle: &AppHandle, event: PeerEvent) {
                 "PeerEvent::DownloadGameFilesBegin",
             );
         }
+        PeerEvent::DownloadGameFileChunkFinished {
+            id,
+            peer_addr,
+            relative_path,
+            offset,
+            length,
+        } => {
+            log::debug!(
+                "PeerEvent::DownloadGameFileChunkFinished received for {id}: \
+                 {relative_path} offset {offset} length {length} from {peer_addr}"
+            );
+        }
         PeerEvent::DownloadGameFilesFinished { id } => {
             handle_download_finished(app_handle, id).await;
         }