Migrate CLI E2E tests to Node.js 26

Run the CLI subprocess suites and benchmark tools as native TypeScript with
node:test, and move them under test/e2e-cli.

Update CI and Compose runners, run local smoke tests on Linux, macOS, and
Windows, and collect source-mapped CLI coverage with c8.

test/e2e-cli/run-cli-e2e.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env sh
+set -eu
+
+TASK="${CLI_E2E_TASK:-test:p2p:ci}"
+
+case "$TASK" in
+  test:p2p-host|test:p2p-peers|test:p2p-sync|test:p2p-automatic-host|test:p2p-replacement|test:p2p-relay-disconnect|test:p2p:ci|test:p2p-three-nodes|test:p2p-upload-download)
+    exec node run-task.ts "$TASK"
+    ;;
+  *)
+    echo "Unknown CLI_E2E_TASK: $TASK" >&2
+    echo "Expected one of: test:p2p-host, test:p2p-peers, test:p2p-sync, test:p2p-automatic-host, test:p2p-replacement, test:p2p-relay-disconnect, test:p2p:ci, test:p2p-three-nodes, test:p2p-upload-download" >&2
+    exit 2
+    ;;
+esac