fix(hooks): resolve the venv path before asking git whether it is tracked

The guard added in 9cdc40e6 was incomplete. `git ls-files` reports paths as they
are indexed and does not follow symlinks, so a repository that commits `.venv` as
a symlink to its own root alongside a tracked `bin/python` gets asked about
`.venv/bin/python` -- a path git has never heard of -- and the answer is
"untracked". The interpreter then runs. Measured on that shape: the planted
executable logged two invocations against 9cdc40e6 and none against this commit.

`repo_ships_interpreter` now resolves the bin directory with `cd -P`/`pwd -P`,
resolves the worktree root the same way, and asks git about the resolved path
relative to it. The three cases that matter all hold: a plainly committed venv is
still refused, the symlink shape is now refused, and a developer's own untracked
venv still resolves and runs.

`cd -P`/`pwd -P` rather than `realpath` or `readlink -f`, because neither is
portable to a stock macOS.

tests/scripts/codex-hooks.test.js

@@ -319,6 +319,7 @@ function runHermeticPythonPrePush({
   venvName = null,
   venvExit = 0,
   trackVenv = false,
+  trackedSymlinkVenv = false,
   pytestCmd = null,
   overrideStub = false,
   pathPytestVersionLine = null,
@@ -350,6 +351,16 @@ function runHermeticPythonPrePush({
     }
   }
 
+  // The shape that defeats a naive `git ls-files -- .venv/bin/python` check: the
+  // repository commits `.venv` as a symlink to its own root plus a tracked
+  // `bin/python`, so git is asked about a path it has never indexed.
+  if (trackedSymlinkVenv) {
+    writeExecutable(path.join(projectDir, 'bin', 'python'), `#!/bin/sh\n${record}\nexit 0\n`);
+    fs.symlinkSync('.', path.join(projectDir, '.venv'));
+    const added = spawnSync('git', ['add', '-f', '--', 'bin/python', '.venv'], { cwd: projectDir });
+    assert.strictEqual(added.status, 0, added.stderr?.toString());
+  }
+
   // Deliberately does NOT special-case --version: an operator's wrapper would not
   // either, and the recorded calls are what prove the hook never probed it.
   const overrideStubPath = overrideStub ? path.join(tempDir, 'bin', 'wrapper') : null;
@@ -416,7 +427,18 @@ if (
     const { result, calls } = runHermeticPythonPrePush({ venvName: '.venv', trackVenv: true });
     assert.strictEqual(result.status, 0, `${result.stdout}\n${result.stderr}`);
     assert.deepStrictEqual(calls, [], JSON.stringify(calls));
-    assert.match(result.stdout, /it is tracked in this repository/);
+    assert.match(result.stdout, /the repository ships it/);
+  })
+)
+  passed++;
+else failed++;
+
+if (
+  test('pre-push refuses a tracked interpreter reached through a committed symlink', () => {
+    const { result, calls } = runHermeticPythonPrePush({ trackedSymlinkVenv: true });
+    assert.strictEqual(result.status, 0, `${result.stdout}\n${result.stderr}`);
+    assert.deepStrictEqual(calls, [], JSON.stringify(calls));
+    assert.match(result.stdout, /the repository ships it/);
   })
 )
   passed++;