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

[jinyeow]

Problem

nvim-treesitter master is frozen for Neovim 0.11 and crashes on 0.12: its query_predicates.lua calls vim.treesitter's pre-0.12 get_node_text/get_range, throwing attempt to call method 'range' (a nil value) on any injection query — i.e. every markdown edit (render-markdown + the native highlighter both trigger it). checkhealth stayed green because parsers are fine; the break is in the query-predicate layer.

Fix — migrate to main (the 0.12+ rewrite)

• 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' (a default-branch quirk of the archived repo) — the locked rev is what lands a fresh install on main. An already-installed master checkout needs a one-time :lua vim.pack.update({'nvim-treesitter','nvim-treesitter-textobjects'}, { force = true }) (non-interactive; documented in 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 (same af/if/ac/ic, ]m [m ]] [[); incremental selection now native 0.12 (gnn/grn/grm → van/an/in; grc dropped). Explicit language.register() for ps1/cs/sh/javascriptreact.
• 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. Adds tree-sitter.tree-sitter-cli to winget/packages.json.
• Docs: CLAUDE.md treesitter + offline-install decisions; nvim/README prereqs.

Verification (isolated sandbox)

Lockfile → fresh vim.pack.add lands on main (install=function); parsers compile via the zig shim; and the original crash path — vim.treesitter.get_parser():parse(true) (injections) on a markdown buffer — returns ok, no error.

⚠️ Interactive confirmation still recommended after merge+pull (highlight, vaf/]m/gnn across lua/cs/ps1/markdown/org). The offline installer's parser step is master-specific and flagged as needing rework (out of scope).

[jinyeow]

Codex cross-model review (read-only, second opinion)

Verdict: no HIGH findings. Codex confirmed the pinned main APIs and argument shapes are correct — require('nvim-treesitter').install, config.get_installed('parsers'), vim.treesitter.start() in the FileType autocmd, indentexpr, and the textobjects select_textobject(query, group) / move.goto_*(query, group) calls (including that move accepts either a string or a list).

MEDIUM

1. nvim/README.md — stale master reference (Plugins table still said the treesitter plugins are pinned to master). ✅ Fixed → main.
2. nvim/README.md — stale ensure_installed (offline-install table referenced the removed API + the master compile path). ✅ Fixed → parser-list wording + a note that the offline parser/org steps need rework for main.
3. treesitter.lua — silent pcall(vim.treesitter.start, …) hides permanent parser failures as if merely pending. Kept deliberately (rationale): the FileType autocmd fires per buffer, and on a fresh machine parsers are still compiling async — a vim.notify there would spam during the normal compile window. A permanent breakage still surfaces as missing highlight + :checkhealth nvim-treesitter. Open to revisiting if preferred.

LOW

• nvim/zigcc.cmd — %* reparsed via an env var, so unusual unquoted args with CMD metacharacters could be altered. Kept: tree-sitter build's real invocation passes quoted paths (verified end-to-end — parsers compile), so the known call site is safe. A structurally-argv-preserving wrapper would need a compiled exe; not worth it for the one caller.

Fixes pushed in c1be5fd. (Findings are Codex's; I applied/decided per the above.)