fix(server): do not throw on unparsable DB_URL when building backup arguments

`buildPostgresLaunchArguments` already guarded URL parsing with
`URL.canParse`, but the returned password was read from a second,
unguarded `new URL(databaseConfig.url)` call. A `DB_URL` that `new URL`
cannot parse, such as a unix domain socket URL like
`socket://user:password@/path/to/socket?db=immich`, made the database
backup job fail immediately with `TypeError: Invalid URL`. The password
is now collected alongside the username inside the guarded branch and
falls back to an empty string, matching the existing username fallback.

Closes #30331

server/src/services/database-backup.service.spec.ts

@@ -565,6 +565,48 @@ describe(DatabaseBackupService.name, () => {
         `);
       });
     });
+
+    describe('using an unparsable URL', () => {
+      beforeEach(() => {
+        // unix domain socket URLs cannot be parsed by `new URL`
+        const dbUrl = 'socket://mypg:mypwd@/var/run/postgresql?db=myimmich';
+        const configMock = {
+          getEnv: () => ({ database: { config: { connectionType: 'url', url: dbUrl }, skipMigrations: false } }),
+          getWorker: () => ImmichWorker.Api,
+          isDev: () => false,
+        } as unknown as any;
+
+        sut = new DatabaseBackupService(
+          mocks.logger as never,
+          mocks.storage as never,
+          configMock as never,
+          mocks.systemMetadata as never,
+          mocks.process,
+          mocks.database as never,
+          mocks.user as never,
+          mocks.cron as never,
+          mocks.job as never,
+          void 0 as never,
+        );
+      });
+
+      it('should fallback to reasonable defaults', async () => {
+        await expect(sut.buildPostgresLaunchArguments('pg_dump')).resolves.toMatchInlineSnapshot(`
+          {
+            "args": [
+              "socket://mypg:mypwd@/var/run/postgresql?db=myimmich",
+              "--clean",
+              "--if-exists",
+            ],
+            "bin": "/usr/lib/postgresql/14/bin/pg_dump",
+            "databaseMajorVersion": 14,
+            "databasePassword": "",
+            "databaseUsername": "postgres",
+            "databaseVersion": "14.10 (Debian 14.10-1.pgdg120+1)",
+          }
+        `);
+      });
+    });
   });
 
   describe('uploadBackup', () => {

server/src/services/database-backup.service.ts

@@ -129,6 +129,7 @@ export class DatabaseBackupService {
 
     const args: string[] = [];
     let databaseUsername;
+    let databasePassword;
 
     if (isUrlConnection) {
       if (bin !== 'pg_dump') {
@@ -142,16 +143,19 @@ export class DatabaseBackupService {
         parsedUrl.searchParams.delete('uselibpqcompat');
 
         databaseUsername = parsedUrl.username || parsedUrl.searchParams.get('user');
+        databasePassword = parsedUrl.password;
 
         url = parsedUrl.href;
       }
 
       // assume typical values if we can't parse URL or not present
       databaseUsername ??= 'postgres';
+      databasePassword ??= '';
 
       args.push(url);
     } else {
       databaseUsername = databaseConfig.username;
+      databasePassword = databaseConfig.password;
 
       args.push(
         '--username',
@@ -214,7 +218,7 @@ export class DatabaseBackupService {
       bin: `/usr/lib/postgresql/${databaseMajorVersion}/bin/${bin}`,
       args,
       databaseUsername,
-      databasePassword: isUrlConnection ? new URL(databaseConfig.url).password : databaseConfig.password,
+      databasePassword,
       databaseVersion,
       databaseMajorVersion,
     };