🐛(summary) complete webm support

When duration is not reported in the files metadata,
we directly infer the duration from the audio packets.
This prevents errors on webm files.

Very simple audio & video test files have been added
that cover relevant usecases to prevent regressions.

src/summary/tests/unit/test_file_service.py

@@ -0,0 +1,30 @@
+"""Unit tests for the file service."""
+
+from pathlib import Path
+
+import pytest
+
+from summary.core.file_service import get_media_duration
+
+
+@pytest.mark.parametrize(
+    "filename, duration",
+    [
+        ("audio-sample-android-chrome.webm", 2.2795),
+        ("audio-sample-android-firefox.ogg", 2.3025),
+        ("audio-sample-android.m4a", 1.38),
+        ("audio-sample-chromium.webm", 2.65),
+        ("audio-sample-firefox.ogg", 2.0865),
+        ("audio-sample-ios-browser.webm", 2.6229),
+        ("audio-sample-ios.m4a", 1.408),
+        ("audio-sample-mac-os-safari.webm", 2.3049),
+        ("video-sample-visio.mp4", 5.34059),
+    ],
+)
+def test_validate_duration_supports_all_used_file_formats(
+    filename: str, duration: float
+) -> None:
+    """Validate duration for Safari iPhone WebM files without format duration."""
+    audio_path = Path(__file__).parent.parent / "assets" / filename
+
+    assert get_media_duration(audio_path) == pytest.approx(duration, 1e-3)