fix(modules/anomaly/tmux): fix config handling in run scripts (#629)

## Description

Fix custom tmux config handling. Two bugs:

1. `TMUX_CONFIG="${TMUX_CONFIG}"` - Terraform substitutes config inline,
bash interprets `set -g` etc as shell commands
2. `printf "$TMUX_CONFIG"` - `%` in `bind %` treated as format specifier


## Type of Change

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

## Module Information

**Path:** `registry/anomaly/modules/tmux`  
**New version:** 1.0.4  
**Breaking change:** [x] No

## Testing & Validation

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

## Related Issues

None

registry/anomaly/modules/tmux/README.md

@@ -15,7 +15,7 @@ up a default or custom tmux configuration with session save/restore capabilities
 ```tf
 module "tmux" {
   source   = "registry.coder.com/anomaly/tmux/coder"
-  version  = "1.0.3"
+  version  = "1.0.4"
   agent_id = coder_agent.example.id
 }
 ```
@@ -39,7 +39,7 @@ module "tmux" {
 ```tf
 module "tmux" {
   source        = "registry.coder.com/anomaly/tmux/coder"
-  version       = "1.0.3"
+  version       = "1.0.4"
   agent_id      = coder_agent.example.id
   tmux_config   = ""                        # Optional: custom tmux.conf content
   save_interval = 1                         # Optional: save interval in minutes
@@ -78,7 +78,7 @@ This module can provision multiple tmux sessions, each as a separate app in the
 ```tf
 module "tmux" {
   source      = "registry.coder.com/anomaly/tmux/coder"
-  version     = "1.0.3"
+  version     = "1.0.4"
   agent_id    = var.agent_id
   sessions    = ["default", "dev", "anomaly"]
   tmux_config = <<-EOT

registry/anomaly/modules/tmux/main.tf

@@ -55,7 +55,7 @@ resource "coder_script" "tmux" {
   display_name = "tmux"
   icon         = "/icon/terminal.svg"
   script = templatefile("${path.module}/scripts/run.sh", {
-    TMUX_CONFIG   = var.tmux_config
+    TMUX_CONFIG   = base64encode(var.tmux_config)
     SAVE_INTERVAL = var.save_interval
   })
   run_on_start = true

registry/anomaly/modules/tmux/scripts/run.sh

@@ -4,7 +4,7 @@ BOLD='\033[0;1m'
 
 # Convert templated variables to shell variables
 SAVE_INTERVAL="${SAVE_INTERVAL}"
-TMUX_CONFIG="${TMUX_CONFIG}"
+TMUX_CONFIG=$(echo -n "${TMUX_CONFIG}" | base64 -d)
 
 # Function to install tmux
 install_tmux() {
@@ -73,7 +73,7 @@ setup_tmux_config() {
   mkdir -p "$config_dir"
 
   if [ -n "$TMUX_CONFIG" ]; then
-    printf "$TMUX_CONFIG" > "$config_file"
+    printf "%s" "$TMUX_CONFIG" > "$config_file"
     printf "$${BOLD}Custom tmux configuration applied at {$config_file} \n\n"
   else
     cat > "$config_file" << EOF