fix: guard completeValidationRun and drop dead superseded_by column

- completeValidationRun now checks status='running' in WHERE clause and
  throws if no row was updated (catches double-complete and invalid runId)
- Remove unused superseded_by column from v46 CREATE TABLE DDL
- Add migration v47 to DROP COLUMN superseded_by from existing DBs
- Bump SCHEMA_VERSION to 47

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

src/resources/extensions/sf/sf-db.js

@@ -114,7 +114,7 @@ function openRawDb(path) {
 	loadProvider();
 	return new DatabaseSync(path);
 }
-const SCHEMA_VERSION = 46;
+const SCHEMA_VERSION = 47;
 function indexExists(db, name) {
 	return !!db
 		.prepare(
@@ -2558,7 +2558,6 @@ function migrateSchema(db) {
 					started_at TEXT,
 					completed_at TEXT,
 					created_at TEXT NOT NULL,
-					superseded_by TEXT,
 					FOREIGN KEY (milestone_id) REFERENCES milestones(id)
 				)
 			`);
@@ -2585,6 +2584,25 @@ function migrateSchema(db) {
 				":applied_at": new Date().toISOString(),
 			});
 		}
+		if (currentVersion < 47) {
+			// Drop unused superseded_by column from validation_runs.
+			// The column was never written or queried — dead schema from v46.
+			const cols = db
+				.prepare("PRAGMA table_info(validation_runs)")
+				.all()
+				.map((c) => c.name);
+			if (cols.includes("superseded_by")) {
+				db.exec(
+					"ALTER TABLE validation_runs DROP COLUMN superseded_by",
+				);
+			}
+			db.prepare(
+				"INSERT INTO schema_version (version, applied_at) VALUES (:version, :applied_at)",
+			).run({
+				":version": 47,
+				":applied_at": new Date().toISOString(),
+			});
+		}
 		db.exec("COMMIT");
 	} catch (err) {
 		db.exec("ROLLBACK");
@@ -7304,7 +7322,9 @@ export function completeValidationRun({
 	findings = "",
 }) {
 	if (!currentDb) throw new SFError(SF_STALE_STATE, "sf-db: No database open");
-	currentDb
+	const status =
+		verdict === "pass" ? "pass" : verdict === "fail" ? "fail" : "error";
+	const result = currentDb
 		.prepare(
 			`UPDATE validation_runs SET
 			 status = :status,
@@ -7312,15 +7332,21 @@ export function completeValidationRun({
 			 rationale = :rationale,
 			 findings = :findings,
 			 completed_at = datetime('now')
-			 WHERE run_id = :run_id`,
+			 WHERE run_id = :run_id AND status = 'running'`,
 		)
 		.run({
 			":run_id": runId,
-			":status": verdict === "pass" ? "pass" : verdict === "fail" ? "fail" : "error",
+			":status": status,
 			":verdict": verdict ?? "",
 			":rationale": rationale ?? "",
 			":findings": findings ?? "",
 		});
+	if (result.changes === 0) {
+		throw new SFError(
+			SF_STALE_STATE,
+			`sf-db: completeValidationRun: no running validation run found for run_id=${runId}`,
+		);
+	}
 }
 
 /**