refactor(sync): move the delta feed's domain pages out of its route

src/__tests__/baselines/source-function-lines.json

@@ -1,7 +1,7 @@
 {
   "$comment": "Production functions over 200 lines, keyed \"file :: name\", and their length. Maintained by src/__tests__/source-size-ratchet.test.ts.",
-  "count": 380,
-  "total": 133935,
+  "count": 379,
+  "total": 133508,
   "entries": {
     "app/achievements/page.tsx :: AchievementsPage": 206,
     "app/api/admin/backups/upload/route.ts :: apiHandler(arg)": 314,
@@ -52,7 +52,6 @@
     "app/api/nutrients/batch/route.ts :: postBatch": 304,
     "app/api/onboarding/complete/route.ts :: completeNeedsFlow": 218,
     "app/api/record-settings/[family]/route.ts :: apiHandler(arg) #2": 262,
-    "app/api/sync/changes/route.ts :: apiHandler(arg)": 427,
     "app/api/user/ai-provider/route.ts :: apiHandler(arg) #2": 248,
     "app/api/withings/callback/route.ts :: apiHandler(arg)": 247,
     "app/auth/login/page.tsx :: LoginPage": 576,

src/__tests__/baselines/version-stamp-comments.json

@@ -1,7 +1,7 @@
 {
   "$comment": "Comment lines that open with a release version, per file under src/. Maintained by src/__tests__/version-stamp-ratchet.test.ts.",
-  "count": 2915,
-  "total": 9853,
+  "count": 2914,
+  "total": 9848,
   "entries": {
     "__tests__/account-payload-consumer-guard.test.ts": 2,
     "__tests__/acting-account-boundary-guard.test.ts": 7,
@@ -533,7 +533,6 @@
     "app/api/strava/credentials/route.ts": 1,
     "app/api/strava/disconnect/route.ts": 1,
     "app/api/strava/status/route.ts": 1,
-    "app/api/sync/changes/route.ts": 5,
     "app/api/sync/state/route.ts": 2,
     "app/api/telegram/webhook/__tests__/route.test.ts": 3,
     "app/api/user/ai-provider/__tests__/legacy-private-host.test.ts": 1,

src/__tests__/medication-intake-tracking-guard.test.ts

@@ -63,7 +63,7 @@ const INTAKE_MAY_SEE_EVERY_ROW: Record<string, string> = {
   "app/api/export/route.ts": "export of the recorded history",
   "lib/export/medications-backup.ts": "backup of the recorded history",
   "app/api/sync/state/route.ts": "sync watermarks, no rate",
-  "app/api/sync/changes/route.ts":
+  "lib/sync/changes/read-rows.ts":
     "delta feed mirroring the recorded rows to a paired client, no rate",
   "lib/jobs/measurement-tombstone-cleanup.ts": "tombstone purge",
   "lib/ai/coach/tools/availability.ts":