Add Spotify-powered Telescope music MVP

[bautistaaa]

Summary

• add a provider-neutral Lua architecture with a Spotify Web API adapter
• add PKCE authentication, permission-restricted token persistence, search, playback, queue, and now-playing controls
• add a debounced Telescope picker with optional image.nvim/chafa artwork previews and automatic capability detection
• add health diagnostics and documentation for lazy.nvim, vim.pack, mini.deps, packer.nvim, and vim-plug
• add CI coverage for plugin loading, Telescope integration, utilities, and the local OAuth callback server

Testing

• stylua --check .
• headless Neovim smoke test on stable Neovim
• headless Telescope picker creation test
• local Spotify OAuth callback integration test
• :checkhealth jam