fix(scan): use Path.name instead of Path.stem to preserve dots in env names

Closes #37. Path.stem strips the final dotted segment of directory names,
causing silent collisions for dirs like "prod.v2" and "prod". Path.name
preserves the full basename.

Author: DevForge Engineer

src/configdrift/cli.py

@@ -267,7 +267,7 @@ def scan(
         # Use directory basenames as env names
         dir_mapping = {}
         for d in dirs:
-            env_name = Path(d).stem
+            env_name = Path(d).name
             dir_mapping[env_name] = d
     else:
         console.print(

tests/test_cli.py

@@ -405,6 +405,40 @@ def test_scan_env_and_toml_dirs(self):
             data = json.loads(result.stdout)
             assert "prod" in data
 
+    def test_scan_dir_names_with_dots_preserved(self):
+        """Dir names containing dots must not be truncated by Path.stem."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            dev_dir = Path(tmpdir) / "dev"
+            prod_us = Path(tmpdir) / "prod.us"
+            prod_eu = Path(tmpdir) / "prod.eu"
+            dev_dir.mkdir()
+            prod_us.mkdir()
+            prod_eu.mkdir()
+            (dev_dir / "c.yaml").write_text(yaml.dump({"host": "localhost"}))
+            (prod_us / "c.yaml").write_text(yaml.dump({"host": "us.example.com"}))
+            (prod_eu / "c.yaml").write_text(yaml.dump({"host": "eu.example.com"}))
+
+            # Table output: all 3 envs must appear as distinct columns
+            result = runner.invoke(
+                app,
+                ["scan", str(dev_dir), str(prod_us), str(prod_eu)],
+            )
+            assert result.exit_code == 0, f"STDOUT: {result.stdout}"
+            assert "dev →" in result.stdout, "Baseline 'dev' should appear in table"
+            assert "prod.us" in result.stdout, f"Missing prod.us in output:\n{result.stdout}"
+            assert "prod.eu" in result.stdout, f"Missing prod.eu in output:\n{result.stdout}"
+
+            # JSON output: both targets must be separate keys (not collapsed)
+            result2 = runner.invoke(
+                app,
+                ["scan", str(dev_dir), str(prod_us), str(prod_eu), "--output", "json"],
+            )
+            assert result2.exit_code == 0, f"STDOUT: {result2.stdout}"
+            data = json.loads(result2.stdout)
+            assert "prod.us" in data, f"Missing prod.us in {list(data.keys())}"
+            assert "prod.eu" in data, f"Missing prod.eu in {list(data.keys())}"
+            assert len(data) == 2, f"Expected 2 targets, got {len(data)}: {list(data.keys())}"
+
     def test_scan_no_changes_env_skipped_in_table(self):
         """Scan with multiple envs where one has no changes."""
         with tempfile.TemporaryDirectory() as tmpdir: