Multi-root workspace: always uses first folder; no way to switch active root

[FernandoCelmer]

Problem

currentWorkspaceFolder() in settings.service.ts always returns vscode.workspace.workspaceFolders?.[0]?.uri.fsPath. In a multi-root workspace this silently pins every pycodeloop serve invocation — and every file-tool jail — to the first folder in the list, regardless of which file the user is editing.

This matters for:

• The cwd passed to RpcClient (and therefore to the spawned process).
• The workspace jail that limits read_file/write_file/etc. to one root.
• resolveWorkspacePath(), which expands ${workspaceFolder} to the same fixed path.

Steps to reproduce / context

1. Open a multi-root workspace with folders [frontend, backend].
2. Open the CodeLoop sidebar.
3. Ask the agent to read a file in backend/.
4. The agent's working directory is frontend/ and ${workspaceFolder} resolves to frontend/, causing path-not-found errors or the agent reading the wrong tree.

Expected behavior

The extension should either:

• Follow the active editor's workspace folder (via vscode.workspace.getWorkspaceFolder(vscode.window.activeTextEditor?.document.uri)), or
• Expose a command / status-bar picker to let the user select the active root, similar to how the Python extension lets you select the interpreter per-folder.

The chosen root should be re-evaluated (or at least re-queried) each time ensureClient() spawns a new process.