refactor: extract _assets.py and _utils.py from __init__.py (PR-2/8) (#2543)

* refactor: extract _assets.py and _utils.py from __init__.py

Move bundle path resolution and version lookup into _assets.py (stdlib only,
zero internal imports), and system utilities (subprocess, tool detection,
file operations) into _utils.py (imports only from ._console). Re-export all
moved symbols from __init__.py for backward compatibility. Update
test_check_tool.py to patch both specify_cli and specify_cli._utils namespaces
since constants are now defined in _utils.

* style: apply PR-1 review patterns to _assets.py and _utils.py

- Add module docstring to _assets.py (stdlib-only, zero internal imports)
- Add blank line after `from __future__ import annotations` in both files
- Replace `Optional[X]` with `X | None` throughout _utils.py (PEP 604)
- Remove unused `Optional` import from _utils.py
- Use explicit re-export form (`X as X`) for public symbols in __init__.py
- Remove unused `subprocess` and `tempfile` imports from __init__.py (moved to _utils.py)

tests/test_check_tool.py

@@ -22,7 +22,9 @@ class TestCheckToolClaude:
         fake_missing = tmp_path / "nonexistent" / "claude"
 
         with patch("specify_cli.CLAUDE_LOCAL_PATH", fake_claude), \
+             patch("specify_cli._utils.CLAUDE_LOCAL_PATH", fake_claude), \
              patch("specify_cli.CLAUDE_NPM_LOCAL_PATH", fake_missing), \
+             patch("specify_cli._utils.CLAUDE_NPM_LOCAL_PATH", fake_missing), \
              patch("shutil.which", return_value=None):
             assert check_tool("claude") is True
 
@@ -36,7 +38,9 @@ class TestCheckToolClaude:
         fake_migrate = tmp_path / "nonexistent" / "claude"
 
         with patch("specify_cli.CLAUDE_LOCAL_PATH", fake_migrate), \
+             patch("specify_cli._utils.CLAUDE_LOCAL_PATH", fake_migrate), \
              patch("specify_cli.CLAUDE_NPM_LOCAL_PATH", fake_npm_claude), \
+             patch("specify_cli._utils.CLAUDE_NPM_LOCAL_PATH", fake_npm_claude), \
              patch("shutil.which", return_value=None):
             assert check_tool("claude") is True
 
@@ -45,7 +49,9 @@ class TestCheckToolClaude:
         fake_missing = tmp_path / "nonexistent" / "claude"
 
         with patch("specify_cli.CLAUDE_LOCAL_PATH", fake_missing), \
+             patch("specify_cli._utils.CLAUDE_LOCAL_PATH", fake_missing), \
              patch("specify_cli.CLAUDE_NPM_LOCAL_PATH", fake_missing), \
+             patch("specify_cli._utils.CLAUDE_NPM_LOCAL_PATH", fake_missing), \
              patch("shutil.which", return_value="/usr/local/bin/claude"):
             assert check_tool("claude") is True
 
@@ -54,7 +60,9 @@ class TestCheckToolClaude:
         fake_missing = tmp_path / "nonexistent" / "claude"
 
         with patch("specify_cli.CLAUDE_LOCAL_PATH", fake_missing), \
+             patch("specify_cli._utils.CLAUDE_LOCAL_PATH", fake_missing), \
              patch("specify_cli.CLAUDE_NPM_LOCAL_PATH", fake_missing), \
+             patch("specify_cli._utils.CLAUDE_NPM_LOCAL_PATH", fake_missing), \
              patch("shutil.which", return_value=None):
             assert check_tool("claude") is False
 
@@ -68,7 +76,9 @@ class TestCheckToolClaude:
         tracker = MagicMock()
 
         with patch("specify_cli.CLAUDE_LOCAL_PATH", fake_missing), \
+             patch("specify_cli._utils.CLAUDE_LOCAL_PATH", fake_missing), \
              patch("specify_cli.CLAUDE_NPM_LOCAL_PATH", fake_npm_claude), \
+             patch("specify_cli._utils.CLAUDE_NPM_LOCAL_PATH", fake_npm_claude), \
              patch("shutil.which", return_value=None):
             result = check_tool("claude", tracker=tracker)
 

tests/test_utils_assets_imports.py

@@ -0,0 +1,21 @@
+"""Regression guard: utility and asset symbols importable from specify_cli."""
+from specify_cli import (
+    run_command, check_tool, is_git_repo, init_git_repo,
+    handle_vscode_settings, merge_json_files,
+    get_speckit_version,
+    CLAUDE_LOCAL_PATH, CLAUDE_NPM_LOCAL_PATH,
+)
+from pathlib import Path
+
+def test_utils_symbols_importable():
+    assert callable(check_tool)
+    assert callable(merge_json_files)
+    assert callable(is_git_repo)
+
+def test_get_speckit_version_returns_string():
+    version = get_speckit_version()
+    assert isinstance(version, str) and len(version) > 0
+
+def test_claude_paths_are_paths():
+    assert isinstance(CLAUDE_LOCAL_PATH, Path)
+    assert isinstance(CLAUDE_NPM_LOCAL_PATH, Path)