fix: address all HIGH-severity code quality audit findings

- lsp/server.go: track request goroutines in inflight WaitGroup to
  prevent use-after-close writes on shutdown
- lsp/llm_client_registry.go: acquire write lock before calling build()
  to eliminate TOCTOU race on cache population
- lsp/handlers_codeaction.go: resolveSimplifyCodeAction now uses
  PromptCodeActionSimplify{System,User} (was wrongly using rewrite prompts)
- askcli/taskexport.go: remove exported MustParseTaskExport to prevent
  panic on malformed external input; move to unexported test helper
- cmd/ask/main.go: print error to stderr before os.Exit
- llm/{openai,ollama,openrouter}.go: add interface satisfaction assertions
- integrationtests/ask_test.go: replace type assertions with errors.As
  for robust exec.ExitError unwrapping

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/cmd/ask/main.go b/cmd/ask/main.go
index 72b67e3..afab992 100644
--- a/cmd/ask/main.go
+++ b/cmd/ask/main.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"os"
 
 	"codeberg.org/snonux/hexai/internal/askcli"
@@ -11,6 +12,8 @@ func main() {
 	d := askcli.NewDispatcher(nil)
 	code, err := d.Dispatch(context.Background(), os.Args[1:], os.Stdin, os.Stdout, os.Stderr)
 	if err != nil {
+		// Print the internal error so callers get a useful diagnostic message.
+		fmt.Fprintln(os.Stderr, err)
 		os.Exit(code)
 	}
 	if code != 0 {