feat(SIENTIAPDE-2202): write timestamp and quality per OPC server

- write_timestamp/write_quality come from the command, then the server
  document (connectors/opc-servers, read even when the reads have the
  connection open, same 60 s cache), then the WRITE_TIMESTAMP/WRITE_QUALITY
  env defaults.
- The quality comes from the command's `quality` (the prediction status:
  Good/Bad/Uncertain, Good when absent); an unknown one is a bad_quality error.
- A server that refuses them (BadWriteNotSupported, e.g. Kepware) gets the
  value written again alone and is remembered until restart: one warning and
  opc_write_value_only_fallback_total per server.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/unit/connection/test_servers.py

@@ -149,3 +149,67 @@ async def test_mongo_errors_propagate_to_the_caller():
 
     with pytest.raises(RuntimeError, match='mongo down'):
         await resolver.resolve('1', {})
+
+
+# --- SIENTIAPDE-2202: write options on the server document ---
+
+
+@pytest.mark.asyncio
+async def test_write_options_come_from_the_connector():
+    resolver = make_resolver(
+        connector={**CONNECTOR, 'write_timestamp': False, 'write_quality': True},
+        opc_server={**OPC_SERVER, 'write_timestamp': True},
+    )
+
+    assert await resolver.write_options('1') == {'write_timestamp': False, 'write_quality': True}
+
+
+@pytest.mark.asyncio
+async def test_write_options_come_from_opc_servers_without_tag_database():
+    resolver = make_resolver(opc_server={**OPC_SERVER, 'write_quality': False})
+
+    assert await resolver.write_options('1') == {'write_quality': False}
+
+
+@pytest.mark.asyncio
+async def test_only_boolean_write_options_count():
+    resolver = make_resolver(
+        connector={**CONNECTOR, 'write_timestamp': 'false', 'write_quality': 0}
+    )
+
+    assert await resolver.write_options('1') == {}
+
+
+@pytest.mark.asyncio
+async def test_write_options_are_read_even_with_a_live_pooled_connection():
+    pooled = {'url': 'opc.tcp://read:1', 'server_uri': 'urn:read', 'use_security': True}
+    resolver = make_resolver(connector={**CONNECTOR, 'write_timestamp': False}, pooled=pooled)
+
+    assert await resolver.resolve('1', {}) == pooled
+    assert await resolver.write_options('1') == {'write_timestamp': False}
+
+
+@pytest.mark.asyncio
+async def test_write_options_share_the_lookup_cache():
+    resolver = make_resolver(connector={**CONNECTOR, 'write_quality': False})
+
+    await resolver.resolve('1', {})
+    await resolver.write_options('1')
+
+    assert resolver.mongo.find_one.await_count == 1
+
+
+@pytest.mark.asyncio
+async def test_write_options_of_an_unknown_server_are_empty():
+    resolver = make_resolver()
+
+    assert await resolver.write_options('9') == {}
+
+
+@pytest.mark.asyncio
+async def test_write_options_never_raise():
+    resolver = make_resolver()
+    resolver.mongo.find_one = AsyncMock(side_effect=RuntimeError('mongo down'))
+
+    assert await resolver.write_options('1') == {}
+    assert 'mongo down' in resolver.logger.warning.call_args.args[0]