fix(integrations): cursor-agent honors executable/extra-args env overrides (#3265)

* fix(integrations): cursor-agent ignores executable/extra-args env overrides

cursor-agent's build_exec_args() hardcoded self.key as argv[0] and never
called _apply_extra_args_env_var(), so the documented
SPECKIT_INTEGRATION_CURSOR_AGENT_EXECUTABLE (issue #2596) and
SPECKIT_INTEGRATION_CURSOR_AGENT_EXTRA_ARGS (issue #2595) hooks were
silently dropped — unlike every other CLI-dispatch integration (codex,
devin). Route argv[0] through _resolve_executable() and apply the
extra-args hook after the mandatory headless flags, mirroring the twins.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* test(integrations): pin extra-args insertion order for cursor-agent

Per Copilot feedback: the extra-args override test only asserted the
injected tokens were present, not that they land before Spec Kit's
canonical --model / --output-format flags. Exercise build_exec_args with
both a model and JSON output and assert the extra args are inserted
before --model / --output-format (and the canonical flags stay intact and
paired). Verified this fails if the _apply_extra_args_env_var call is
moved after the flag extends.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

src/specify_cli/integrations/cursor_agent/__init__.py

@@ -75,7 +75,15 @@ class CursorAgentIntegration(SkillsIntegration):
         either drops tool calls or exits non-zero on the first approval
         prompt.
         """
-        args = [self.key, "-p", "--trust", "--approve-mcps", "--force", prompt]
+        args = [
+            self._resolve_executable(),
+            "-p",
+            "--trust",
+            "--approve-mcps",
+            "--force",
+            prompt,
+        ]
+        self._apply_extra_args_env_var(args)
         if model:
             args.extend(["--model", model])
         if output_json: