fix: catch OSError in streaming dispatch_command() for missing/unexecutable binaries

The streaming branch only caught KeyboardInterrupt but not OSError.
If the binary is removed between shutil.which() and subprocess.run()
(a TOCTOU race), an OSError propagates unhandled.

Author: Quratulain-bilal

src/specify_cli/integrations/base.py

@@ -401,6 +401,12 @@ def dispatch_command(
                     "stdout": "",
                     "stderr": "Interrupted by user",
                 }
+            except OSError as exc:
+                return {
+                    "exit_code": 1,
+                    "stdout": "",
+                    "stderr": f"Failed to execute command: {exc}",
+                }
             return {
                 "exit_code": result.returncode,
                 "stdout": "",

src/specify_cli/integrations/copilot/__init__.py

@@ -314,6 +314,12 @@ def dispatch_command(
                     "stdout": "",
                     "stderr": "Interrupted by user",
                 }
+            except OSError as exc:
+                return {
+                    "exit_code": 1,
+                    "stdout": "",
+                    "stderr": f"Failed to execute command: {exc}",
+                }
             return {
                 "exit_code": result.returncode,
                 "stdout": "",