fix: time window regex misses fuzzy quantifiers like 'last few hours'

The relative-time regex only matched digits between 'last/past' and
the unit, so 'last few hours' fell through to dateparser which then
found the bare word 'hours' and resolved it as midnight local time.

Extended the regex to capture 'few', 'couple of', 'several', 'a few'
as approximate quantifiers, mapped to 3 units each. Numeric expressions
and bare 'last hour' still work as before.

app/services/diagnose.py

@@ -25,16 +25,20 @@ except ImportError:
 
 
 _RELATIVE_RE = re.compile(
-    r"\b(?:last|past)\s+(\d+)?\s*(minute|hour|day|week)s?\b",
+    r"\b(?:last|past)\s+(?:(?P<n>\d+)|(?P<approx>a\s+few|few|couple(?:\s+of)?|several))?\s*(?P<unit>minute|hour|day|week)s?\b",
     re.IGNORECASE,
 )
 _RELATIVE_UNITS = {"minute": 1, "hour": 60, "day": 1440, "week": 10080}
+# Fuzzy quantifiers map to a reasonable span so "last few hours" → 3h window
+_APPROX_N = 3
 
 
 def _relative_window(match: re.Match) -> tuple[str, str]:
     """Convert a relative time match to (since_iso, until_iso)."""
-    n = int(match.group(1) or 1)
-    unit = match.group(2).lower()
+    n_str = match.group("n")
+    approx = match.group("approx")
+    unit = match.group("unit").lower()
+    n = int(n_str) if n_str else (_APPROX_N if approx else 1)
     minutes = n * _RELATIVE_UNITS[unit]
     return _last_n_minutes(minutes), _now_iso()