Add User Model Service and Temporal Recall for MeMind V0.1.

Introduce UMS ingest/snapshot pipeline, Context Planner with multi-source recall, runtime context injection, canonical user mapping, and session snapshot loading on auth/me.

Co-authored-by: Cursor <cursoragent@cursor.com>

user-model-service/session-snapshot.mjs

@@ -0,0 +1,30 @@
+import { resolveCanonicalUserId } from './canonical-user.mjs';
+import { getActiveSnapshot } from './snapshot.mjs';
+
+/**
+ * Session bootstrap payload for /auth/me (RFC: 5～10KB snapshot at session start).
+ *
+ * @param {import('mysql2/promise').Pool | null | undefined} pool
+ * @param {string} userId
+ * @param {string} [projection]
+ */
+export async function loadSessionUserModelSnapshot(pool, userId, projection = 'default') {
+  if (!pool?.query || !userId) return null;
+  const canonicalUserId = resolveCanonicalUserId(userId);
+  const snap = await getActiveSnapshot(pool, canonicalUserId, projection);
+  if (!snap) return null;
+  return {
+    snapshot_id: snap.snapshot_id,
+    user_id: snap.user_id,
+    projection: snap.projection,
+    profile_version: snap.profile_version,
+    fast_revision: snap.fast_revision,
+    content_hash: snap.content_hash,
+    byte_size: snap.byte_size,
+    stale_after_sec: snap.stale_after_sec,
+    loaded_at_hint: 'session_start',
+    core: snap.core,
+    meta: snap.meta,
+    ...(canonicalUserId !== userId ? { canonical_user_id: canonicalUserId } : {}),
+  };
+}