feat: rebrand CCS as Claude Codex Switch (#1658)

Closes #1657

scripts/completion/ccs.bash

@@ -1,4 +1,4 @@
-# Bash completion for CCS (Claude Code Switch)
+# Bash completion for CCS (Claude Codex Switch)
 # Compatible with bash 3.2+
 
 _ccs_completion() {

scripts/completion/ccs.fish

@@ -1,4 +1,4 @@
-# Fish completion for CCS (Claude Code Switch)
+# Fish completion for CCS (Claude Codex Switch)
 
 function __fish_ccs_complete
     set -l tokens_before_current (commandline -opc)

scripts/completion/ccs.ps1

@@ -1,4 +1,4 @@
-# PowerShell completion for CCS (Claude Code Switch)
+# PowerShell completion for CCS (Claude Codex Switch)
 
 function Invoke-CcsCompletionBackend {
     param(

scripts/completion/ccs.zsh

@@ -1,6 +1,6 @@
 #compdef ccs
 
-# Zsh completion for CCS (Claude Code Switch)
+# Zsh completion for CCS (Claude Codex Switch)
 
 _ccs() {
   local current