fix: address code scanning findings

- enforce a second image trust boundary in the provider builders:
  buildClaudeUserContent/buildCodexInputItems only accept files inside
  the upload store or the run's working directory (CodeQL path
  injection)
- drop an always-true selectedProject check in handleSubmit
- remove the unused resume option from spawnCursor

src/components/chat/hooks/useChatComposerState.ts

@@ -586,9 +586,8 @@ export function useChatComposerState({
         if (textareaRef.current) {
           textareaRef.current.style.height = 'auto';
         }
-        if (selectedProject) {
-          safeLocalStorage.removeItem(`draft_input_${selectedProject.projectId}`);
-        }
+        // selectedProject is guaranteed by the guard at the top of handleSubmit.
+        safeLocalStorage.removeItem(`draft_input_${selectedProject.projectId}`);
         return;
       }