feat: use isproj-only project files and local settings

Closes #6

src/apps/desktop/tests/start-screen.test.mjs

@@ -4,7 +4,7 @@ import { displayPath, groupRecentProjects, renderStartScreen } from '../src/star
 import { allowProjectTransition } from '../src/project-transition.ts';
 
 const recent = (id, year, month, day, name = id) => ({
-  id, path: `C:\\projects\\${id}\\package-project.json`, displayName: name,
+  id, path: `C:\\projects\\${id}\\InstallerProject.isproj`, displayName: name,
   lastOpenedAt: new Date(year, month - 1, day, 10).getTime() / 1000, available: true,
 });
 
@@ -18,8 +18,8 @@ test('recent projects are grouped in local calendar order and searchable by name
 });
 
 test('extended Windows paths are displayed without changing their UNC semantics', () => {
-  assert.equal(displayPath('\\\\?\\C:\\apps\\project.json'), 'C:\\apps\\project.json');
-  assert.equal(displayPath('\\\\?\\UNC\\server\\share\\project.json'), '\\\\server\\share\\project.json');
+  assert.equal(displayPath('\\\\?\\C:\\apps\\project.isproj'), 'C:\\apps\\project.isproj');
+  assert.equal(displayPath('\\\\?\\UNC\\server\\share\\project.isproj'), '\\\\server\\share\\project.isproj');
 });
 
 test('start screen has left recent projects and right actions without fabricated entries', () => {