fix(completion): close shell completion review gaps

scripts/completion/README.md

@@ -137,7 +137,7 @@ $ ccs auth show <TAB>
 work      personal  team      --json
 
 $ ccs api <TAB>
-create    discover  copy      export  import  remove
+create    list      discover  copy    export  import  remove
 ```
 
 ### Backend Contract

scripts/completion/ccs.fish

@@ -7,6 +7,9 @@ function __fish_ccs_complete
     end
 
     set -l current (commandline -ct)
+    if test -n "$current"; and test (count $tokens_before_current) -gt 0; and test "$tokens_before_current[-1]" = "$current"
+        set -e tokens_before_current[-1]
+    end
 
     set -l script_file (status filename)
     set -l repo_root (realpath (dirname $script_file)/../.. 2>/dev/null)