feat(neovim): add vim-tidal plugin for TidalCycles live coding

[etrobert-bot]

What

Adds a tidal plugin module to neovim-wrapped that packages vim-tidal (not in nixpkgs) and wires it into the plugin set.

• Pins vim-tidal to its latest commit (e440fe5) via buildVimPlugin + fetchFromGitHub — the v1.x tags are old; it's a stable vimscript plugin.
• Sets g:tidal_target = "tmux" so pattern lines are pasted into a tmux pane running GHCi+Tidal (pairs with the existing vim-tmux-navigator workflow).

Why

Companion to a TidalCycles flake in the electronic-music project. The split is deliberate:

• Pattern language (GHCi + tidal) and audio engine (SuperDirt) live in that project's nix develop.
• The editor integration lives here, matching the per-plugin module pattern.

In tmux mode vim-tidal only ships lines to a running GHCi — it does not boot one — so the workflow is: superdirt in one pane, tidal (GHCi booted with Tidal) in another, send lines from a .tidal buffer.

Verification

• nix build .#neovim-wrapped succeeds; vim-tidal builds.
• Headless nvim: g:tidal_target == "tmux", :TidalSend exists, .tidal files get filetype tidal.

🤖 Generated with Claude Code

[etrobert-bot]

Reviewed thoroughly — checked out the branch, ran nix build .#neovim-wrapped, exercised the built nvim headlessly, and verified every claim against the vim-tidal upstream source. Everything holds up:

• vim-tidal really isn't in nixpkgs (nix eval nixpkgs#vimPlugins finds no tidal plugin).
• e440fe5 is the current HEAD of the default branch, dated 2023-06-02 (matches the version).
• The v1.x tags are indeed old — latest tag 1.4.8 is from 2020-04-01, ~3 years older than the pinned commit.
• g:tidal_target = "tmux" is a genuine behavior change, not a no-op: on nvim the upstream default is "terminal" (if has('nvim')…), so this is necessary for the tmux workflow.
• Build succeeds; headless nvim confirms g:tidal_target == "tmux", :TidalSend exists, and .tidal files get filetype tidal. <localleader>s maps to TidalLineSend/TidalRegionSend per ftplugin/tidal.vim.
• extraPackages = [ tmux ] is required (tmux-mode shells out to tmux); the overlap with vim-tmux-navigator's tmux dep is harmless and per-plugin self-containment matches the repo convention.

No correctness issues and nothing extraneous in the derivation. Just three optional consistency nits below — all non-blocking.