Add SXT experiment type (#316)

* Add SXT experiment type

* Update 2026_03_18_ExperimentType_sxt.sql

Author: gfrn

schemas/ispyb/updates/2026_03_18_ExperimentType_sxt.sql

@@ -0,0 +1,7 @@
+INSERT IGNORE INTO SchemaStatus (scriptName, schemaStatus) VALUES ('2026_03_18_ExperimentType_sxt.sql', 'ONGOING');
+
+INSERT INTO ExperimentType (
+  experimentTypeId, name, proposalType, active
+) VALUES (47, 'Soft X-Ray Tomography', 'em', 1), (48, 'CryoSIM', 'em', 1);
+
+UPDATE SchemaStatus SET schemaStatus = 'DONE' WHERE scriptName = '2026_03_18_ExperimentType_sxt.sql';