perf: batch page embeddings via /api/embed and upsert before pruning stale points

- embed_batch now issues one batched /api/embed request (the old loop
  made one /api/embeddings round-trip per chunk) with a per-text
  fallback that preserves None-for-failed semantics
- update_from_page embeds all chunks in that single call and stores
  them in one Qdrant batch upsert (upsert_points)
- reindex order reversed: upsert new points first, then prune stale ids
  (deterministic uuid5 ids make overwrite safe) so a mid-way failure no
  longer leaves the page with zero vectors
- VectorUpdateSummary gains status (success/partial/failed) and
  chunks_skipped; all-embeddings-failed keeps old vectors and reports
  failure instead of success=True

Measured on a 7-chunk page ingest (local server, llm_tester):
~375ms -> ~181ms median over 3 runs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QbFZyDvYksazX6nYQYZ67L

tests/test_tenant_scoping.py

@@ -41,6 +41,9 @@ def mock_qdrant():
     qdrant.search_vectors = AsyncMock(return_value=[])
     qdrant.search_with_expiry_filter = AsyncMock(return_value=[])
     qdrant.upsert_vector = AsyncMock(return_value=True)
+    qdrant.upsert_points = AsyncMock(side_effect=lambda collection_name, points: len(points))
+    qdrant.scroll_all_points = AsyncMock(return_value=[])
+    qdrant.delete_by_ids = AsyncMock(return_value=0)
     qdrant.delete_by_filter = AsyncMock(return_value=0)
     return qdrant
 
@@ -49,6 +52,9 @@ def mock_qdrant():
 def mock_ollama():
     ollama = MagicMock()
     ollama.embed = AsyncMock(return_value=[0.1] * 768)
+    ollama.embed_batch = AsyncMock(
+        side_effect=lambda texts, **kw: [[0.1] * 768 for _ in texts]
+    )
     ollama.embed_text = AsyncMock(return_value=[0.1] * 768)
     ollama.generate_text = AsyncMock(return_value="{}")
     return ollama
@@ -148,8 +154,8 @@ class TestVectorLegScoping:
 
         assert summary.success is False
         assert "outside user" in (summary.error_message or "")
-        mock_qdrant.upsert_vector.assert_not_awaited()
-        mock_qdrant.delete_by_filter.assert_not_awaited()
+        mock_qdrant.upsert_points.assert_not_awaited()
+        mock_qdrant.delete_by_ids.assert_not_awaited()
 
     async def test_update_from_page_rejects_sibling_prefix_namespace(
         self, vector_service, mock_qdrant, mock_wiki
@@ -163,7 +169,7 @@ class TestVectorLegScoping:
         summary = await vector_service.update_from_page(page_id=43, user=TENANT)
 
         assert summary.success is False
-        mock_qdrant.upsert_vector.assert_not_awaited()
+        mock_qdrant.upsert_points.assert_not_awaited()
 
     async def test_update_from_page_accepts_own_namespace(
         self, vector_service, mock_qdrant, mock_wiki
@@ -177,7 +183,7 @@ class TestVectorLegScoping:
 
         assert summary.success is True
         assert (
-            mock_qdrant.upsert_vector.await_args.kwargs["collection_name"]
+            mock_qdrant.upsert_points.await_args.kwargs["collection_name"]
             == TENANT_COLLECTION
         )