feat: add test framework, unit tests, and GitLab CI pipeline

- Add pytest config in backend/pyproject.toml with asyncio mode and coverage
- Add backend/requirements-test.txt with pytest, pytest-cov, pytest-asyncio, aiosqlite
- Write 86 backend unit tests covering auth (JWT tokens), schemas (Pydantic
  models), config (Settings env overrides), log_parser (log parsing, IP
  resolution, geo data), models (SQLAlchemy table definitions + column
  defaults), and theme export
- Add Vitest config for Angular frontend (vitest.config.ts, src/test-setup.ts)
- Add .gitlab-ci.yml with stages: backend-test, frontend-test, backend-lint,
  docker-build, and quality-gate
- CI enforces 10% minimum coverage threshold for backend

backend/tests/test_log_parser.py

@@ -0,0 +1,140 @@
+"""Tests for log_parser — IP resolution, log line parsing, and geo lookups."""
+
+import os
+import tempfile
+import pytest
+
+from app.log_parser import parse_log_line, resolve_client_ip, _COUNTRY_CENTROIDS
+
+
+class TestParseLogLine:
+    """Tests for parse_log_line()."""
+
+    def test_valid_json_line(self):
+        line = '{"remote_addr": "192.168.1.1", "method": "GET"}'
+        result = parse_log_line(line)
+        assert result is not None
+        assert result["remote_addr"] == "192.168.1.1"
+        assert result["method"] == "GET"
+
+    def test_empty_line_returns_none(self):
+        assert parse_log_line("") is None
+
+    def test_whitespace_only_returns_none(self):
+        assert parse_log_line("   ") is None
+
+    def test_invalid_json_returns_none(self):
+        assert parse_log_line("not json at all") is None
+
+    def test_partial_json_returns_none(self):
+        assert parse_log_line('{"remote_addr": ') is None
+
+    def test_strips_whitespace(self):
+        line = '  {"key": "value"}  \n'
+        result = parse_log_line(line)
+        assert result is not None
+        assert result["key"] == "value"
+
+
+class TestResolveClientIp:
+    """Tests for resolve_client_ip()."""
+
+    def test_remote_addr_without_xff(self):
+        entry = {"remote_addr": "203.0.113.5"}
+        assert resolve_client_ip(entry) == "203.0.113.5"
+
+    def test_xff_single_ip(self):
+        entry = {
+            "remote_addr": "10.0.0.1",
+            "x_forwarded_for": "203.0.113.50",
+        }
+        assert resolve_client_ip(entry) == "203.0.113.50"
+
+    def test_xff_multiple_ips_returns_leftmost(self):
+        entry = {
+            "remote_addr": "10.0.0.1",
+            "x_forwarded_for": "203.0.113.100, 10.1.2.3, 172.16.0.5",
+        }
+        assert resolve_client_ip(entry) == "203.0.113.100"
+
+    def test_xff_dash_falls_back_to_remote_addr(self):
+        entry = {"remote_addr": "192.168.0.1", "x_forwarded_for": "-"}
+        assert resolve_client_ip(entry) == "192.168.0.1"
+
+    def test_missing_fields_returns_empty(self):
+        entry = {}
+        assert resolve_client_ip(entry) == ""
+
+    def test_xff_with_whitespace(self):
+        entry = {
+            "remote_addr": "10.0.0.1",
+            "x_forwarded_for": " 203.0.113.75 ",
+        }
+        assert resolve_client_ip(entry) == "203.0.113.75"
+
+
+class TestCountryCentroids:
+    """Tests for _COUNTRY_CENTROIDS data integrity."""
+
+    def test_centroids_are_float_tuples(self):
+        for code, coords in _COUNTRY_CENTROIDS.items():
+            assert isinstance(coords, tuple)
+            assert len(coords) == 2
+            assert isinstance(coords[0], float)
+            assert isinstance(coords[1], float)
+
+    def test_known_countries_present(self):
+        expected = {"US", "GB", "DE", "FR", "JP", "AU", "BR", "CA", "IN"}
+        assert expected.issubset(_COUNTRY_CENTROIDS.keys())
+
+    def test_centroid_values_are_reasonable(self):
+        """Latitudes should be in [-90, 90], longitudes in [-180, 180]."""
+        for code, (lat, lon) in _COUNTRY_CENTROIDS.items():
+            assert -90 <= lat <= 90, f"{code} latitude {lat} out of range"
+            assert -180 <= lon <= 180, f"{code} longitude {lon} out of range"
+
+
+class TestParseLogFile:
+    """Tests for parse_log_file() — reads from real temp files."""
+
+    def test_parses_multiple_lines(self, tmp_path):
+        log_content = (
+            '{"remote_addr": "1.2.3.4"}\n'
+            '{"remote_addr": "5.6.7.8"}\n'
+            '{"remote_addr": "1.2.3.4"}\n'
+        )
+        log_file = tmp_path / "test.log"
+        log_file.write_text(log_content)
+
+        from app.log_parser import parse_log_file
+        result = parse_log_file(str(log_file))
+        # Should have 2 unique IPs (1.2.3.4 appears twice)
+        assert "1.2.3.4" in result["unique_ips"]
+        assert "5.6.7.8" in result["unique_ips"]
+        assert len(result["unique_ips"]) == 2
+
+    def test_skips_invalid_lines(self, tmp_path):
+        log_content = (
+            '{"remote_addr": "1.2.3.4"}\n'
+            'not valid json\n'
+            '\n'
+            '{"remote_addr": "5.6.7.8"}\n'
+        )
+        log_file = tmp_path / "test.log"
+        log_file.write_text(log_content)
+
+        from app.log_parser import parse_log_file
+        result = parse_log_file(str(log_file))
+        assert len(result["unique_ips"]) == 2
+
+    def test_xff_takes_precedence(self, tmp_path):
+        log_content = (
+            '{"remote_addr": "10.0.0.1", "x_forwarded_for": "203.0.113.1"}\n'
+        )
+        log_file = tmp_path / "test.log"
+        log_file.write_text(log_content)
+
+        from app.log_parser import parse_log_file
+        result = parse_log_file(str(log_file))
+        assert "203.0.113.1" in result["unique_ips"]
+        assert "10.0.0.1" not in result["unique_ips"]