fix(settings): сохранять результат операций базы при вторичных сбоях

shared/api/system-database.test.ts

@@ -26,3 +26,15 @@ test("restore needs literal receipt; malformed/false/204/HTTP error never retry"
   calls=0;globalThis.fetch=async()=>{calls++;return Response.json({error:"restore unknown"},{status:503})};await assert.rejects(restoreSystemDatabaseBackup("https://backend.test",dump),/restore unknown/);assert.equal(calls,1)
  }finally{globalThis.fetch=original}
 })
+
+test("backup warning header is strict and malformed metadata preserves valid archive with warning",async()=>{
+ const original=globalThis.fetch;try{
+  const warnings={listenerError:"listener warning",schedulerError:"scheduler warning",eventError:"event warning"}
+  globalThis.fetch=async()=>new Response("PGDMPfixture",{headers:{"X-System-Database-Outcome":encodeURIComponent(JSON.stringify(warnings))}})
+  assert.deepEqual((await downloadSystemDatabaseBackup("https://backend.test")).warnings,warnings)
+  for(const header of ["%","false",encodeURIComponent(JSON.stringify({listenerError:4})),encodeURIComponent(JSON.stringify({error:"failed"}))]){
+   globalThis.fetch=async()=>new Response("PGDMPfixture",{headers:{"X-System-Database-Outcome":header}})
+   const result=await downloadSystemDatabaseBackup("https://backend.test");assert.equal(await result.blob.text(),"PGDMPfixture");assert.match(result.warnings.eventError!,/не подтверждены/)
+  }
+ }finally{globalThis.fetch=original}
+})