Chooser: handle mismatch between config workspaces and actual macOS spaces

[baby-joel]

Problem

The space chooser (Ctrl+Space) shows all workspaces from config.json, but the user may have fewer actual macOS Spaces than configured workspaces. Selecting a workspace that doesn't have a corresponding macOS Space silently does nothing.

Example

Config has 5 workspaces (main, okwai, zettelkasten, slack, wallpapers) but user only has 3 macOS Spaces. Spaces 4 and 5 show in the chooser but can't be navigated to.

Options

1. Filter to actual spaces — cap choices at wp.spaceCount(). Simple, no confusion.
2. Show all, mark missing — grey out uncreated spaces, maybe offer to create them on selection.
3. Auto-create spaces — if user selects space 4 but only 3 exist, create it first then navigate.

Context

Introduced in the chooser implementation (PR #36, wp-module: v2). Related to #18 (spaces can get reordered) — the mapping between config index and macOS Space index is fragile in general.