chore: add githooks to guard against unexpected commits (#546)

Co-authored-by: Michael Brooks <mbrooks@slack-corp.com>

Author: zimeg

.claude/CLAUDE.md

@@ -207,6 +207,7 @@ See [`.github/STYLE_GUIDE.md`](../.github/STYLE_GUIDE.md) for conventions on com
 - `go.mod` - Go module dependencies and minimum Go version (see `go.mod` for current version)
 - `.circleci/config.yml` - CircleCI workflows for CI/CD pipeline
 - `.github/workflows/` - GitHub Actions for automated testing and releases
+- `.githooks/` - Opt-in Git hooks (enable with `git config core.hooksPath .githooks`)
 
 ## Commit Message Format
 

.githooks/pre-commit

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+# Copyright 2022-2026 Salesforce, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e
+
+# Guard against committing directly to main
+branch="$(git rev-parse --abbrev-ref HEAD)"
+if [ "$branch" = "main" ]; then
+    echo "error: commits directly to main are not allowed. Use a development branch."
+    exit 1
+fi
+
+# Run linter on staged changes
+cd "$(git rev-parse --show-toplevel)" || exit 1
+go tool golangci-lint run

.github/MAINTAINERS_GUIDE.md

@@ -207,6 +207,7 @@ Certain things are common during development and require a few commands.
 **Task outline:**
 
 - [Cloning the project](#cloning-the-project)
+  - [Git hooks](#git-hooks)
 - [Initializing the project](#initializing-the-project)
 - [Testing](#testing)
   - [Module and unit tests](#module-and-unit-tests)
@@ -233,6 +234,19 @@ git clone https://github.com/slackapi/slack-cli.git
 cd slack-cli/
 ```
 
+#### Git hooks
+
+Opt-in Git hooks are available in the `.githooks/` directory. To enable them:
+
+```zsh
+git config core.hooksPath .githooks
+```
+
+The pre-commit hook will:
+
+- Block commits directly to the `main` branch
+- Run `go tool golangci-lint run` to lint before committing
+
 ### Initializing the project
 
 When you first clone the project or after you major updates to the project, it's