test(core): Swift oracle — the filius-ipad core built on Linux as the reference

tools/swift-oracle builds the unchanged Swift runtime (pinned 3b5ded0)
in Docker and replays JSON scenarios; the TypeScript engine must produce
the same trace events, results and end state. Five scenarios, 884
events, identical.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/swift-oracle/run.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+# Replays every scenario under packages/core/test/scenarios in the Swift core
+# and writes the reference result next to it (<name>.swift.json).
+# Needs Docker; the TypeScript tests only read the written files.
+set -eu
+here="$(cd "$(dirname "$0")" && pwd)"
+root="$(cd "$here/../.." && pwd)"
+[ -d "$here/Sources/FiliusCore" ] || "$here/fetch-upstream.sh"
+docker run --rm -v "$root:/work" -w /work/tools/swift-oracle swift:6.1-jammy \
+    sh -c 'swift build -q 2>&1 | grep -v "Sendable\|^ *|\|^ *\`" ; .build/debug/Oracle /work/packages/core/test/scenarios'