feat: relocate import tools into studio and harden catalog/furnidata integrity

- Move /admin/import/* tools under /admin/studio/* and add studio nav, layout and tabs
- Add shared catalog maintenance panel plus a /admin/studio/maintenance tab
- Make furnidata reconciliation overwrite conflicting entries with the
  DB-authoritative items_base classname/id (surfaced via fixedConflicts)
- Add furnidata_translate_enabled setting to skip the heavy localized
  furnidata build during import (manual build-languages still forces it)
- Update staff smoke contract test for the studio hub

src/lib/services/import-live.test.ts

@@ -180,8 +180,8 @@ describeGuard("live furni import / catalog ID consistency (sandbox DB)", () => {
 
 		const before = buildMaps(await readFurniData());
 		// Genuine id conflicts (our spriteId is owned by a different classname
-		// in the file) are left untouched by design — they are a separate
-		// pre-existing data problem, not part of this fix.
+		// in the file) are resolved in favour of items_base: the entry keeps its
+		// id but its classname is overwritten with the items_base classname.
 		let conflicts = 0;
 		let missing = 0;
 		for (const row of rows) {
@@ -205,7 +205,8 @@ describeGuard("live furni import / catalog ID consistency (sandbox DB)", () => {
 
 		const result = await reconcileFurniDataWithItemsBase();
 		expect(result.fixedIds).toBe(idMisBefore);
-		expect(result.conflicts).toBe(conflicts);
+		expect(result.fixedConflicts).toBe(conflicts);
+		expect(result.conflicts).toBe(0);
 		expect(result.missing).toBe(missing);
 
 		// Mirror the function's contract exactly: rows whose id IS keyed in the
@@ -218,7 +219,8 @@ describeGuard("live furni import / catalog ID consistency (sandbox DB)", () => {
 		// furnidata file can only hold one id per classname, so a duplicate
 		// classname can never satisfy this invariant for all its rows. Those
 		// are repaired by the dedicated duplicate-classname tool, not by this
-		// function. Genuine id conflicts are likewise out of scope.
+		// function. Genuine id conflicts are now resolved by overwriting the
+		// entry's classname with the items_base value (see fixedConflicts).
 		const dupClassnames = new Map<string, number>();
 		for (const row of rows)
 			dupClassnames.set(