The codex-skills (x2) and output-styles tests assert Windows junction paths
and were already failing the Ubuntu Pester job on main (pre-existing, not
introduced by this branch). Guard them -Skip:(-not $IsWindows), matching the
existing -Module all test, so #27's Ubuntu check is green independently of the
identical fix in #26. On Windows they run unchanged.

* fix(nvim): migrate nvim-treesitter master -> main for Neovim 0.12

master is frozen for Neovim 0.11 and crashes on 0.12: its query_predicates
call vim.treesitter's pre-0.12 get_node_text/get_range, throwing
"attempt to call method 'range' (a nil value)" on any injection query
(every markdown edit). main is the 0.12+ rewrite and the fix.

- plugins.lua: repin both plugins to version='main'.
- nvim-pack-lock.json: pin the main revs. vim.pack.add checks out master on a
  fresh install even with version='main' (default-branch quirk of the archived
  repo); the locked rev is what makes a fresh install land on main. An already
  installed master checkout needs a one-time
  `:lua vim.pack.update({...}, { force = true })` (see CLAUDE.md).
- treesitter.lua: rewritten for the main/native API - drop configs.setup{};
  install() diffed against config.get_installed(); per-buffer
  vim.treesitter.start() + indentexpr in a FileType autocmd; textobjects via
  nvim-treesitter-textobjects.select/.move; incremental selection now native
  0.12 (gnn/grn/grm -> van/an/in; grc dropped). Explicit language.register()
  for ps1/cs/sh/javascriptreact (main drops master's ft->lang table).
- nvim/zigcc.cmd + treesitter.lua CC: main compiles via the tree-sitter CLI,
  whose cc crate can't call `zig cc` directly (multi-word CC; forced msvc
  triple needs the Windows SDK). The shim rewrites the triple to
  x86_64-windows-gnu and forwards to zig cc - zig stays the sole compiler, no
  LLVM/MSVC. Requires winget tree-sitter.tree-sitter-cli (added to packages.json).
- Docs: CLAUDE.md treesitter + offline-install decisions, nvim/README prereqs.

Verified end-to-end in an isolated sandbox: lockfile -> fresh install on main,
parsers compile via the zig shim, and markdown injection parse no longer crashes.

* docs+style(nvim): fix stale master refs and stylua formatting

Addresses Codex review of the treesitter migration:
- nvim/README.md: Plugins table said the treesitter plugins are pinned to
  `master` (now `main`); the offline-install table referenced the removed
  `ensure_installed` API and described the master compile path — corrected,
  with a note that the offline parser/org steps need rework for `main`.
- treesitter.lua: apply stylua formatting (one parser/filetype per line) so
  the `stylua --check nvim/` CI gate passes.

* test(setup): guard Windows-only junction tests for Linux CI

The codex-skills (x2) and output-styles tests assert Windows junction paths
and were already failing the Ubuntu Pester job on main (pre-existing, not
introduced by this branch). Guard them -Skip:(-not $IsWindows), matching the
existing -Module all test, so #27's Ubuntu check is green independently of the
identical fix in #26. On Windows they run unchanged.