feat: add disable_autoupdater variable to control auto-updates (#545)

## Description

Claude-Code auto-updates itself unless the `DISABLE_AUTOUPDATER` env is
set. This PR adds a `disable_autoupdater` variable which allows the user
to disable claude-code's auto updating feature. This should resolve the
issue where claude-code updates itself when a user defines a specific
claude-code version to be installed which was confusing for the end
user.

<!-- Briefly describe what this PR does and why -->

## Type of Change

- [ ] New module
- [ ] New template
- [X] Bug fix
- [ ] Feature/enhancement
- [ ] Documentation
- [ ] Other

## Module Information

<!-- Delete this section if not applicable -->

**Path:** `registry/coder/modules/claude-code`  
**New version:** `v4.2.0`  
**Breaking change:** [ ] Yes [X] No

## Testing & Validation

- [X] Tests pass (`bun test`)
- [X] Code formatted (`bun fmt`)
- [X] Changes tested locally

## Related Issues

<!-- Link related issues or write "None" if not applicable -->

registry/coder/modules/claude-code/README.md

@@ -13,7 +13,7 @@ Run the [Claude Code](https://docs.anthropic.com/en/docs/agents-and-tools/claude
 ```tf
 module "claude-code" {
   source         = "registry.coder.com/coder/claude-code/coder"
-  version        = "4.1.0"
+  version        = "4.2.0"
   agent_id       = coder_agent.example.id
   workdir        = "/home/coder/project"
   claude_api_key = "xxxx-xxxxx-xxxx"
@@ -70,7 +70,7 @@ data "coder_parameter" "ai_prompt" {
 
 module "claude-code" {
   source   = "registry.coder.com/coder/claude-code/coder"
-  version  = "4.1.0"
+  version  = "4.2.0"
   agent_id = coder_agent.example.id
   workdir  = "/home/coder/project"
 
@@ -106,7 +106,7 @@ Run and configure Claude Code as a standalone CLI in your workspace.
 ```tf
 module "claude-code" {
   source              = "registry.coder.com/coder/claude-code/coder"
-  version             = "4.1.0"
+  version             = "4.2.0"
   agent_id            = coder_agent.example.id
   workdir             = "/home/coder"
   install_claude_code = true
@@ -129,7 +129,7 @@ variable "claude_code_oauth_token" {
 
 module "claude-code" {
   source                  = "registry.coder.com/coder/claude-code/coder"
-  version                 = "4.1.0"
+  version                 = "4.2.0"
   agent_id                = coder_agent.example.id
   workdir                 = "/home/coder/project"
   claude_code_oauth_token = var.claude_code_oauth_token
@@ -202,7 +202,7 @@ resource "coder_env" "bedrock_api_key" {
 
 module "claude-code" {
   source   = "registry.coder.com/coder/claude-code/coder"
-  version  = "4.1.0"
+  version  = "4.2.0"
   agent_id = coder_agent.example.id
   workdir  = "/home/coder/project"
   model    = "global.anthropic.claude-sonnet-4-5-20250929-v1:0"
@@ -259,7 +259,7 @@ resource "coder_env" "google_application_credentials" {
 
 module "claude-code" {
   source   = "registry.coder.com/coder/claude-code/coder"
-  version  = "4.1.0"
+  version  = "4.2.0"
   agent_id = coder_agent.example.id
   workdir  = "/home/coder/project"
   model    = "claude-sonnet-4@20250514"

registry/coder/modules/claude-code/main.tf

@@ -114,6 +114,12 @@ variable "claude_code_version" {
   default     = "latest"
 }
 
+variable "disable_autoupdater" {
+  type        = bool
+  description = "Disable Claude Code automatic updates. When true, Claude Code will stay on the installed version."
+  default     = false
+}
+
 variable "claude_api_key" {
   type        = string
   description = "The API key to use for the Claude Code server."
@@ -274,6 +280,14 @@ resource "coder_env" "claude_api_key" {
   value    = var.claude_api_key
 }
 
+resource "coder_env" "disable_autoupdater" {
+  count = var.disable_autoupdater ? 1 : 0
+
+  agent_id = var.agent_id
+  name     = "DISABLE_AUTOUPDATER"
+  value    = "1"
+}
+
 locals {
   # we have to trim the slash because otherwise coder exp mcp will
   # set up an invalid claude config