fix(core-dsr): flip processingRestrictedAt in soft-delete for self role

PayloadDataDelete.deleteSubjectData('soft') was NULLing PII fields and
emitting RESTRICT audit entries, but never setting processingRestrictedAt
on self-kind rows — violating GDPR Art. 17 restriction semantics.

softRedactOwnerRows now accepts optional extraData; processOwnerRows
passes { processingRestrictedAt: new Date().toISOString() } when
kind === 'self' and mode === 'soft'. Owner-kind rows are intentionally
excluded (restriction flag belongs on the subject record, not owned rows).

Added two dedicated tests: one asserting the field is present for self,
one asserting it is absent for owner.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

coverage/summary.json

@@ -1,16 +1,16 @@
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-  "generatedAt": "2026-05-19T19:59:56.279Z",
-  "commit": "8068d1b",
+  "generatedAt": "2026-05-19T20:12:30.651Z",
+  "commit": "6606b59",
   "repo": {
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@@ -74,14 +74,14 @@
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