build: add nix devshell and pre-commit hooks

Problem: oil.nvim had no reproducible dev environment. The .envrc
set up a Python venv for the now-removed docgen pipeline, and there
were no pre-commit hooks for local formatting checks.

Solution: add flake.nix with stylua, selene, and prettier in the
devshell. Replace the stale Python .envrc with 'use flake'. Add
.pre-commit-config.yaml with stylua and prettier hooks matching
other plugins in the repo collection.

.envrc

@@ -1,3 +1 @@
-export VIRTUAL_ENV=venv
-layout python
-python -c 'import pyparsing' 2>/dev/null || pip install -r scripts/requirements.txt
+use flake

.pre-commit-config.yaml

@@ -0,0 +1,17 @@
+minimum_pre_commit_version: '3.5.0'
+
+repos:
+  - repo: https://github.com/JohnnyMorganz/StyLua
+    rev: v2.3.1
+    hooks:
+      - id: stylua-github
+        name: stylua (Lua formatter)
+        files: \.lua$
+        pass_filenames: true
+
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: v4.0.0-alpha.8
+    hooks:
+      - id: prettier
+        name: prettier
+        files: \.(md|toml|yaml|yml|sh)$

Makefile

@@ -45,4 +45,4 @@ scripts/benchmark.nvim:
 ## clean: reset the repository to a clean state
 .PHONY: clean
 clean:
-	rm -rf scripts/nvim-typecheck-action venv .testenv perf/tmp profile.json
+	rm -rf scripts/nvim-typecheck-action .testenv perf/tmp profile.json

flake.lock

@@ -0,0 +1,43 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1771207753,
+        "narHash": "sha256-b9uG8yN50DRQ6A7JdZBfzq718ryYrlmGgqkRm9OOwCE=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "d1c15b7d5806069da59e819999d70e1cec0760bf",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs",
+        "systems": "systems"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,29 @@
+{
+  description = "oil.nvim — Neovim file explorer: edit your filesystem like a buffer";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    systems.url = "github:nix-systems/default";
+  };
+
+  outputs =
+    {
+      nixpkgs,
+      systems,
+      ...
+    }:
+    let
+      forEachSystem = f: nixpkgs.lib.genAttrs (import systems) (system: f nixpkgs.legacyPackages.${system});
+    in
+    {
+      devShells = forEachSystem (pkgs: {
+        default = pkgs.mkShell {
+          packages = [
+            pkgs.prettier
+            pkgs.stylua
+            pkgs.selene
+          ];
+        };
+      });
+    };
+}