Multi-root workspaces: project-context commands only ever see `workspaceFolders[0]`

Problem

getWorkspacePath() in src/extension.ts resolves the workspace like this:

function getWorkspacePath(): string | undefined {
	const workspaceFolders = vscode.workspace.workspaceFolders;
	if (!workspaceFolders || workspaceFolders.length === 0) {
		vscode.window.showErrorMessage('No workspace folder open');
		return undefined;
	}
	return workspaceFolders[0].uri.fsPath;
}

Only the first folder of a multi-root workspace is ever considered. In a .code-workspace with several folders, everything outside folder[0] is unreachable by any WinApp command — there is no prompt, no setting, and no error explaining why the app isn't found.

Two things make it worse:

1. winapp.appDirectories can't route around it. isContainedInWorkspace() in src/project-resolver.ts rejects absolute paths and .. traversal, so the setting cannot point at a second root even when the user knows exactly where their app is.
2. winapp.appDirectories has no "scope" declared in package.json, so it defaults to window — a single value for the whole workspace rather than per-folder .vscode/settings.json values.

Meanwhile WinAppDebugAdapterFactory uses session.workspaceFolder, which is folder-scoped — so F5 and the command palette can silently operate on different roots.

Affected commands

Every project-context command routed through resolveProjectDirectory:

• WinApp: Initialize Project
• WinApp: Restore Packages
• WinApp: Update Packages
• WinApp: Generate Manifest
• WinApp: Update Manifest Assets
• WinApp: Add Manifest Execution Alias
• WinApp: Generate Certificate
• WinApp: Unregister Package
• WinApp: Get WinApp Path

Relationship to the winapp run project-mode work

The project-mode change makes winapp.run, winapp.runAdvanced, and the debug adapter multi-root aware, and deliberately leaves the general-purpose primitives behind for reuse:

• getWorkspaceRoots() and per-root scan/aggregate helpers
• root labelling for QuickPick items (applied only when more than one root exists, so single-folder users see no change)
• active-editor-root defaulting

So this issue should be a rewiring rather than a rewrite: point resolveProjectDirectory's dependencies at those helpers.

Scope

• Make resolveProjectDirectory span all workspace roots, reusing the primitives above.
• Replace getWorkspacePath()'s folder[0] assumption for the remaining commands.
• Declare winapp.appDirectories as "scope": "resource" and make isContainedInWorkspace validate per-root, so each folder's .vscode/settings.json can supply its own app directories.
• Extend the existing src/test/project-resolver.test.ts coverage to multi-root cases.

Start with getWorkspacePath() and resolveProjectDirectory in src/extension.ts, then inspect isContainedInWorkspace in src/project-resolver.ts and the existing multi-root primitives described in the issue. Review winapp.appDirectories in package.json and extend src/test/project-resolver.test.ts. Done means project-context commands consider all roots, per-folder app directories are accepted, and multi-root cases pass without changing single-folder behavior.