fix(env): add missing CLIProxy profiles to bash completion and shell validation

- Add iflow, kiro, ghcp, claude to bash completion env block
- Add --shell flag validation matching --format pattern
- Add backtick injection test case

scripts/completion/ccs.bash

@@ -156,7 +156,7 @@ _ccs_completion() {
     case "${prev}" in
       env)
         # Complete with profile names and flags (inline profiles since $cliproxy_profiles is out of scope)
-        local env_opts="--format --shell --help -h gemini codex agy qwen"
+        local env_opts="--format --shell --help -h gemini codex agy qwen iflow kiro ghcp claude"
         if [[ -f ~/.ccs/config.json ]]; then
           env_opts="$env_opts $(jq -r '.profiles | keys[]' ~/.ccs/config.json 2>/dev/null || true)"
         fi