feat: add HTML email body for --send (#48)

Add email.html config flag (default false). When enabled, --send
includes an HTML version of the report body generated via HTMLFormatter
alongside the plain-text part in a multipart/alternative message.

- EmailConfig gains html: bool field
- mailer.build_message/send_report accept rows for HTML generation
- CLI passes rows to send_report
- --init-config generates email.html: false
- README.md and docs/CONFIG.md updated

Bump version to 1.10.0.

Closes #48

tests/test_cli.py

@@ -387,6 +387,21 @@ class TestInitConfig:
 
         assert data["redmine"]["api_key"] == "${REDMINE_API_KEY}"
 
+    @mock.patch.dict(os.environ, VALID_ENV, clear=True)
+    def test_init_config_includes_email_html(self, tmp_path):
+        """--init-config генерирует email.html: false."""
+        import yaml
+
+        config_path = tmp_path / "config.yml"
+        code = main(["--init-config", "--config-path", str(config_path)])
+        assert code == 0
+
+        with open(config_path) as fh:
+            data = yaml.safe_load(fh)
+
+        assert "html" in data["email"]
+        assert data["email"]["html"] is False
+
     @mock.patch.dict(os.environ, {}, clear=True)
     def test_init_config_no_env_vars(self, tmp_path):
         """Без переменных окружения --init-config создаёт скелет."""
@@ -1011,6 +1026,98 @@ class TestSendFlag:
         assert code == 0
 
 
+class TestSendHtmlBody:
+    """Tests for email.html body generation."""
+
+    @mock.patch.dict(os.environ, VALID_ENV, clear=True)
+    @mock.patch("redmine_reporter.cli.fetch_issues_with_spent_time")
+    @mock.patch("redmine_reporter.cli.send_report")
+    @mock.patch("redmine_reporter.cli.get_formatter_by_extension")
+    def test_send_passes_rows_to_send_report(
+        self, mock_get, mock_send, mock_fetch, tmp_path
+    ):
+        """--send передаёт rows в send_report для генерации HTML."""
+        issue = _MockIssue()
+        mock_fetch.return_value = [(issue, 1.0)]
+        mock_formatter = mock.MagicMock()
+        mock_get.return_value = mock_formatter
+
+        config_path = tmp_path / "config.yml"
+        config_path.write_text(
+            "email:\n"
+            "  html: true\n"
+            "  smtp:\n"
+            "    host: smtp.example.com\n"
+            "    port: 587\n"
+            "    user: bot\n"
+            "    password: secret\n"
+            "  from: bot@example.com\n"
+            "  to:\n"
+            "    - boss@example.com\n"
+        )
+
+        output = str(tmp_path / "report.xlsx")
+        code = main(
+            [
+                "--date",
+                "2026-06-01--2026-06-30",
+                "--output",
+                output,
+                "--send",
+                "--config-path",
+                str(config_path),
+            ]
+        )
+        assert code == 0
+
+        _, kwargs = mock_send.call_args
+        assert "rows" in kwargs
+        assert len(kwargs["rows"]) == 1
+
+    @mock.patch.dict(os.environ, VALID_ENV, clear=True)
+    @mock.patch("redmine_reporter.cli.fetch_issues_with_spent_time")
+    @mock.patch("redmine_reporter.cli.send_report")
+    @mock.patch("redmine_reporter.cli.get_formatter_by_extension")
+    def test_send_html_false_does_not_require_html_part(
+        self, mock_get, mock_send, mock_fetch, tmp_path
+    ):
+        """При email.html: false письмо отправляется без HTML-части."""
+        issue = _MockIssue()
+        mock_fetch.return_value = [(issue, 1.0)]
+        mock_formatter = mock.MagicMock()
+        mock_get.return_value = mock_formatter
+
+        config_path = tmp_path / "config.yml"
+        config_path.write_text(
+            "email:\n"
+            "  smtp:\n"
+            "    host: smtp.example.com\n"
+            "    port: 587\n"
+            "    user: bot\n"
+            "    password: secret\n"
+            "  from: bot@example.com\n"
+            "  to:\n"
+            "    - boss@example.com\n"
+        )
+
+        output = str(tmp_path / "report.xlsx")
+        code = main(
+            [
+                "--date",
+                "2026-06-01--2026-06-30",
+                "--output",
+                output,
+                "--send",
+                "--config-path",
+                str(config_path),
+            ]
+        )
+        assert code == 0
+        mock_send.assert_called_once()
+        _, kwargs = mock_send.call_args
+        assert "rows" in kwargs
+
+
 class TestResolveNoTime:
     """Tests for _resolve_no_time()."""