feat: add psagentai agent with deployment and configuration

Initial project setup including the main agent script, configuration
files, profile JSON state, systemd service unit, startup script,
deployment documentation, and Python dependencies.

Includes .env, venv/, and __pycache__/ which should likely be
excluded via .gitignore to avoid committing secrets and artifacts.

venv/lib/python3.11/site-packages/pip/_internal/models/candidate.py

@@ -0,0 +1,27 @@
+from dataclasses import dataclass
+
+from pip._vendor.packaging.version import Version
+from pip._vendor.packaging.version import parse as parse_version
+
+from pip._internal.models.link import Link
+
+
+@dataclass(frozen=True, slots=True)
+class InstallationCandidate:
+    """Represents a potential "candidate" for installation."""
+
+    name: str
+    version: Version
+    link: Link
+    locked: bool
+
+    def __init__(
+        self, name: str, version: str, link: Link, locked: bool = False
+    ) -> None:
+        object.__setattr__(self, "name", name)
+        object.__setattr__(self, "version", parse_version(version))
+        object.__setattr__(self, "link", link)
+        object.__setattr__(self, "locked", locked)
+
+    def __str__(self) -> str:
+        return f"{self.name!r} candidate (version {self.version} at {self.link})"