chore(legacy): mark v0 swipe+listings modules LEGACY in-code

domain.js and encoding.js now carry the legacy notice the README already
states; pending the quarantine/removal decision (design doc, Intentfile
legacy-v0-quarantine intent).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

packages/shared/src/domain.js

@@ -1,5 +1,8 @@
 // SPDX-License-Identifier: MPL-2.0
 // Copyright (c) Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
+// LEGACY v0 (swipe + listings flow) — retained pending a quarantine/removal
+// decision; the v1 product is the Squad Audit engine in ./matching/
+// (see docs/design/squad-audit-v1.adoc). Do not extend this module.
 // Domain models, validation, sanitization, compatibility scoring, and vector encoding
 // for flat-mate student profiles and room listings.
 

packages/shared/src/encoding.js

@@ -1,5 +1,8 @@
 // SPDX-License-Identifier: MPL-2.0
 // Copyright (c) Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
+// LEGACY v0 — retained pending a quarantine/removal decision (see
+// docs/design/squad-audit-v1.adoc); the title-encoding scheme is a
+// self-declared disposable MVP strategy. Do not extend this module.
 // Entity encoding for verisimdb hexad titles. Packs entity payloads into base64url tokens
 // embedded within searchable title strings, enabling text-based entity retrieval.