feat(analysis): _detect_gaps su timestamp consecutivi (> 20 min)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/cerbero_bite/analysis/data_audit.py

@@ -124,3 +124,19 @@ def _expected_ticks(since: datetime, until: datetime) -> int:
     # aligned multiples and would mis-count non-aligned spans.
     span_seconds = (until - first_tick).total_seconds()
     return math.ceil(span_seconds / (_TICK_INTERVAL_MIN * 60))
+
+
+def _detect_gaps(timestamps: list[datetime]) -> tuple[GapRecord, ...]:
+    """Return gaps where consecutive timestamps differ by > threshold."""
+    out: list[GapRecord] = []
+    for prev, nxt in zip(timestamps, timestamps[1:], strict=False):
+        delta_min = int((nxt - prev).total_seconds() // 60)
+        if delta_min > _GAP_THRESHOLD_MIN:
+            out.append(
+                GapRecord(
+                    prev_timestamp=prev,
+                    next_timestamp=nxt,
+                    gap_minutes=delta_min,
+                )
+            )
+    return tuple(out)