feat(publish): add PyPI publish workflow, CLI command, parser integration, and tests

* Introduce publish action with PyPI target detection via MIRRORS
* Resolve version from SemVer git tags on HEAD
* Support preview mode and non-interactive CI usage
* Build and upload artifacts using build + twine with token resolution
* Add CLI wiring (dispatch, command handler, parser)
* Add E2E publish help tests for pkgmgr and nix run
* Add integration tests for publish preview and mirror handling
* Add unit tests for git tag parsing, PyPI URL parsing, workflow preview, and CLI handler
* Clean up dispatch and parser structure while integrating publish

https://chatgpt.com/share/693f0f00-af68-800f-8846-193dca69bd2e

tests/e2e/test_publish_commands.py

@@ -0,0 +1,119 @@
+from __future__ import annotations
+
+import io
+import os
+import shutil
+import subprocess
+import tempfile
+import unittest
+from contextlib import redirect_stdout
+from types import SimpleNamespace
+
+from pkgmgr.cli.commands.publish import handle_publish
+
+
+def _run(cmd: list[str], cwd: str) -> None:
+    subprocess.run(
+        cmd,
+        cwd=cwd,
+        check=True,
+        stdout=subprocess.DEVNULL,
+        stderr=subprocess.DEVNULL,
+    )
+
+
+class TestIntegrationPublish(unittest.TestCase):
+    def setUp(self) -> None:
+        if shutil.which("git") is None:
+            self.skipTest("git is required for this integration test")
+
+        self.tmp = tempfile.TemporaryDirectory()
+        self.repo_dir = self.tmp.name
+
+        # Initialize git repository
+        _run(["git", "init"], cwd=self.repo_dir)
+        _run(["git", "config", "user.email", "ci@example.invalid"], cwd=self.repo_dir)
+        _run(["git", "config", "user.name", "CI"], cwd=self.repo_dir)
+
+        with open(os.path.join(self.repo_dir, "README.md"), "w", encoding="utf-8") as f:
+            f.write("test\n")
+
+        _run(["git", "add", "README.md"], cwd=self.repo_dir)
+        _run(["git", "commit", "-m", "init"], cwd=self.repo_dir)
+        _run(["git", "tag", "-a", "v1.2.3", "-m", "v1.2.3"], cwd=self.repo_dir)
+
+        # Create MIRRORS file with PyPI target
+        with open(os.path.join(self.repo_dir, "MIRRORS"), "w", encoding="utf-8") as f:
+            f.write("https://pypi.org/project/pkgmgr/\n")
+
+    def tearDown(self) -> None:
+        self.tmp.cleanup()
+
+    def test_publish_preview_end_to_end(self) -> None:
+        ctx = SimpleNamespace(
+            repositories_base_dir=self.repo_dir,
+            all_repositories=[
+                {
+                    "name": "pkgmgr",
+                    "directory": self.repo_dir,
+                }
+            ],
+        )
+
+        selected = [
+            {
+                "name": "pkgmgr",
+                "directory": self.repo_dir,
+            }
+        ]
+
+        args = SimpleNamespace(
+            preview=True,
+            non_interactive=False,
+        )
+
+        buf = io.StringIO()
+        with redirect_stdout(buf):
+            handle_publish(args=args, ctx=ctx, selected=selected)
+
+        out = buf.getvalue()
+
+        self.assertIn("[pkgmgr] Publishing repository", out)
+        self.assertIn("[INFO] Publishing pkgmgr for tag v1.2.3", out)
+        self.assertIn("[PREVIEW] Would build and upload to PyPI.", out)
+
+        # Preview must not create dist/
+        self.assertFalse(os.path.isdir(os.path.join(self.repo_dir, "dist")))
+
+    def test_publish_skips_without_pypi_mirror(self) -> None:
+        with open(os.path.join(self.repo_dir, "MIRRORS"), "w", encoding="utf-8") as f:
+            f.write("git@github.com:example/example.git\n")
+
+        ctx = SimpleNamespace(
+            repositories_base_dir=self.repo_dir,
+            all_repositories=[
+                {
+                    "name": "pkgmgr",
+                    "directory": self.repo_dir,
+                }
+            ],
+        )
+
+        selected = [
+            {
+                "name": "pkgmgr",
+                "directory": self.repo_dir,
+            }
+        ]
+
+        args = SimpleNamespace(
+            preview=True,
+            non_interactive=False,
+        )
+
+        buf = io.StringIO()
+        with redirect_stdout(buf):
+            handle_publish(args=args, ctx=ctx, selected=selected)
+
+        out = buf.getvalue()
+        self.assertIn("[INFO] No PyPI mirror found. Skipping publish.", out)