feat(g0v0-migrate): implement g0v0 migration system with plugin support (#97)

For details please view the PR.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

packages/g0v0-migrations/g0v0_migrations/utils.py

@@ -0,0 +1,50 @@
+import json
+from pathlib import Path
+import re
+import tomllib
+
+
+def detect_g0v0_server_path() -> Path | None:
+    """Detect the g0v0 server path from the current working directory to parents.
+
+    Returns:
+        The path to the g0v0 server, or None if not found.
+    """
+    cwd = Path.cwd()
+    for path in [cwd, *list(cwd.parents)]:
+        if (pyproject := (path / "pyproject.toml")).exists():
+            try:
+                content = tomllib.loads(pyproject.read_text(encoding="utf-8"))
+            except tomllib.TOMLDecodeError:
+                continue
+            if "project" in content and content["project"].get("name") == "g0v0-server":
+                return path.resolve()
+
+    return None
+
+
+def get_plugin_id(plugin_path: Path) -> str:
+    """Get the plugin ID from the plugin.json file.
+
+    Args:
+        plugin_path: The path to the plugin directory.
+
+    Returns:
+        The plugin ID.
+
+    Raises:
+    """
+    if not plugin_path.joinpath("plugin.json").exists():
+        raise ValueError(f"No plugin.json found at {plugin_path / 'plugin.json'}.")
+    try:
+        meta = json.loads(plugin_path.joinpath("plugin.json").read_text(encoding="utf-8"))
+    except json.JSONDecodeError as e:
+        raise ValueError(f"Malformed plugin.json at {plugin_path / 'plugin.json'}: {e}")
+    plugin_id = meta.get("id")
+    if plugin_id is None:
+        raise ValueError(f"Could not detect plugin id from {plugin_path / 'plugin.json'}.")
+    if re.match(r"^[a-z0-9\-]+$", plugin_id) is None:
+        raise ValueError(
+            f"Invalid plugin id '{plugin_id}' in {plugin_path / 'plugin.json'}. Must match '^[a-z0-9\\-]+$'."
+        )
+    return plugin_id