ci: add Makefile-driven CI with unit, integration and e2e tests

- add GitHub Actions CI workflow using Makefile targets exclusively
- run unit, integration and e2e tests via `make test`
- publish Docker image to GHCR on SemVer tags
- force-update `stable` git tag after successful release
- add integration test for seed CLI (CSV upsert behavior)
- extend Makefile with test-unit and test-integration targets

https://chatgpt.com/share/694ee54f-b814-800f-a714-e87563e538b7

tests/integration/test_seed_integration.py

@@ -0,0 +1,88 @@
+import csv
+import subprocess
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+
+def run_seed(csv_path: Path, instance: str, database: str, username: str, password: str = "") -> subprocess.CompletedProcess:
+    # Run the real CLI module (integration-style).
+    return subprocess.run(
+        [
+            sys.executable,
+            "-m",
+            "baudolo.seed",
+            str(csv_path),
+            instance,
+            database,
+            username,
+            password,
+        ],
+        text=True,
+        capture_output=True,
+        check=True,
+    )
+
+
+def read_csv_semicolon(path: Path) -> list[dict]:
+    with path.open("r", encoding="utf-8", newline="") as f:
+        reader = csv.DictReader(f, delimiter=";")
+        return list(reader)
+
+
+class TestSeedIntegration(unittest.TestCase):
+    def test_creates_file_and_adds_entry_when_missing(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            p = Path(td) / "databases.csv"
+            self.assertFalse(p.exists())
+
+            cp = run_seed(p, "docker.test", "appdb", "alice", "secret")
+
+            self.assertEqual(cp.returncode, 0, cp.stderr)
+            self.assertTrue(p.exists())
+
+            rows = read_csv_semicolon(p)
+            self.assertEqual(len(rows), 1)
+            self.assertEqual(rows[0]["instance"], "docker.test")
+            self.assertEqual(rows[0]["database"], "appdb")
+            self.assertEqual(rows[0]["username"], "alice")
+            self.assertEqual(rows[0]["password"], "secret")
+
+    def test_replaces_existing_entry_same_keys(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            p = Path(td) / "databases.csv"
+
+            # First add
+            run_seed(p, "docker.test", "appdb", "alice", "oldpw")
+            rows = read_csv_semicolon(p)
+            self.assertEqual(len(rows), 1)
+            self.assertEqual(rows[0]["password"], "oldpw")
+
+            # Replace (same instance+database+username)
+            run_seed(p, "docker.test", "appdb", "alice", "newpw")
+            rows = read_csv_semicolon(p)
+
+            self.assertEqual(len(rows), 1, "Expected replacement, not a duplicate row")
+            self.assertEqual(rows[0]["instance"], "docker.test")
+            self.assertEqual(rows[0]["database"], "appdb")
+            self.assertEqual(rows[0]["username"], "alice")
+            self.assertEqual(rows[0]["password"], "newpw")
+
+    def test_database_empty_string_matches_existing_empty_database(self) -> None:
+        with tempfile.TemporaryDirectory() as td:
+            p = Path(td) / "databases.csv"
+
+            # Add with empty database
+            run_seed(p, "docker.test", "", "alice", "pw1")
+            rows = read_csv_semicolon(p)
+            self.assertEqual(len(rows), 1)
+            self.assertEqual(rows[0]["database"], "")
+
+            # Replace with empty database again
+            run_seed(p, "docker.test", "", "alice", "pw2")
+            rows = read_csv_semicolon(p)
+
+            self.assertEqual(len(rows), 1)
+            self.assertEqual(rows[0]["database"], "")
+            self.assertEqual(rows[0]["password"], "pw2")