Refactor character affiliations to singular form

- Updated character data structure to replace 'affiliations' and 'frAffiliations' with 'affiliation' and 'frAffiliation'.
- Modified related functions and components to accommodate the new structure.
- Adjusted database schema and server-side logic to reflect the changes in character affiliation handling.
- Ensured all references in the UI components and data import/export scripts are updated accordingly.

scripts/import-json.ts

@@ -28,8 +28,8 @@ type CharacterRecord = {
 	frName?: string | null;
 	gender?: string | null;
 	age?: number | null;
-	affiliations?: string[] | string | null;
-	frAffiliations?: string[] | string | null;
+	affiliation?:  string | null;
+	frAffiliation?: string | null;
 	devilFruitId?: string | null;
 	hakiObservation?: boolean;
 	hakiArmament?: boolean;
@@ -123,8 +123,8 @@ function transformCharacterData(item: CharacterRecord) {
 		frName: toNullable(item.frName),
 		gender: toNullable(item.gender),
 		age: toNullable(item.age),
-		affiliations: toJsonArray(item.affiliations),
-		frAffiliations: toJsonArray(item.frAffiliations),
+		affiliation: toNullable(item.affiliation),
+		frAffiliation: toNullable(item.frAffiliation),
 		devilFruitId: toNullable(item.devilFruitId),
 		hakiObservation: !!item.hakiObservation,
 		hakiArmament: !!item.hakiArmament,
@@ -369,8 +369,8 @@ async function importFromJson(): Promise<void> {
 								frName: row.frName,
 								gender: row.gender,
 								age: row.age,
-								affiliations: row.affiliations,
-								frAffiliations: row.frAffiliations,
+								affiliation: row.affiliation,
+								frAffiliation: row.frAffiliation,
 								devilFruitId: row.devilFruitId,
 								hakiObservation: row.hakiObservation,
 								hakiArmament: row.hakiArmament,