feat(harness): nsp memory save-one core — targeted upsert via writer key (D11)

The D11 deviation is a single-row pgvector upsert, not a full vectorstore resync.
Ports memory.py + session/{store,artifacts} + textutil (deps of memory), renamed
psdwp3->nsp. Decision import paths rewired from nsp.session.decisions to nsp.decisions
(our A4 port lives at the top level). session/models.py left UNCHANGED to preserve
the Phase-A ThothII additions (D12/D15 author/summary, D14a grounded_values,
D14b concept_formulas).

New in memory.py:
- memory_vector_record_for_decision(records, decision_seq): the single VectorRecord
  for a chosen decision (reuses memory_vector_records, filtered to one).
- save_one_memory(records, decision_seq, writer, embedder): embeds one record and
  calls writer.upsert_records('memory', [row]) -- NEVER writer.sync (that's the
  full-resync, server-side-only path). Returns the upsert count.

L1: test_memory_save_one (5 tests) pins the contract -- single row, one upsert
call, sync never called, None/0 for unknown seq.

Deferred: the full nsp memory save-one CLI command (config/session loading + the
workstation write-guard) lands when memory_cmd.py is ported alongside the other
CLI commands. The pure D11 core is what L1 can honestly cover here.

harness/nsp/session/artifacts.py

@@ -0,0 +1,39 @@
+from pathlib import Path
+
+from nsp.decisions import DecisionRecord
+from nsp.session.models import SchemaLinking
+
+
+def _find_evidence_file(evidence_root: Path, evidence_id: str) -> str:
+    for match in evidence_root.rglob(f"{evidence_id}.md"):
+        return str(match)
+    return ""
+
+
+def build_evidence_entries(
+    decisions: list[DecisionRecord],
+    linking: SchemaLinking,
+    evidence_root: Path,
+) -> list[dict]:
+    """Elenco {id, file, esito, decision_seq}: evidence citate nello schema linking
+    (esito 'usata') e decisioni esplicite del reviewer (accettata/scartata, che
+    prevalgono sul linking)."""
+    entries: dict[str, dict] = {}
+    for candidate in linking.candidates:
+        for evidence_id in candidate.evidence:
+            entries.setdefault(evidence_id, {
+                "id": evidence_id,
+                "file": _find_evidence_file(evidence_root, evidence_id),
+                "esito": "usata",
+                "decision_seq": candidate.decision_seq,
+            })
+    for d in decisions:
+        if d.type not in ("evidence_accepted", "evidence_rejected"):
+            continue
+        entries[d.subject] = {
+            "id": d.subject,
+            "file": _find_evidence_file(evidence_root, d.subject),
+            "esito": "accettata" if d.type == "evidence_accepted" else "scartata",
+            "decision_seq": d.seq,
+        }
+    return list(entries.values())