pattern: a burst of taps is not a routine (V-468)

Detect had no floor on the interval. Four events minutes apart give gaps
near 0.002 days, every one of them inside the ±50% band, so it proposed a
routine and PhraseRoutine called it "каждый день".

UNIQUE(action, object) makes that unrecoverable: dismissing the bogus
proposal burns the pair, and the real routine behind it can never be
proposed again. It also made hand-QA unsafe — seeding a pattern with four
chat turns poisoned the pair being tested.

The floor is two hours against the median, not a day, because meals, water
and breaks are genuine several-times-a-day habits.

internal/pattern/detector.go

@@ -53,9 +53,31 @@ const MinOnPatternFraction = 0.7
 // a repeat. False negatives cost one more observation and nothing else.
 const MinEvents = 4
 
+// MinIntervalDays — the fastest rhythm that may be called a routine. Two
+// hours.
+//
+// Without a floor, four taps of the same key minutes apart give intervals near
+// 0.002 days. They all sit inside the ±50% band by construction, so the
+// detector proposed a routine and PhraseRoutine worded it as "каждый день"
+// (Vikunja #468). The damage outlives the mistake: UNIQUE(action, object)
+// means dismissing the bogus proposal burns that pair permanently, so the real
+// routine behind it can never be proposed again.
+//
+// Two hours rather than a day, because a genuine habit can run several times a
+// day — meals, water, a break. Anything faster than that is not a habit she
+// should be proposing to remind him about; the loop rules already cover that
+// range, and they are rules, not guesses. It is checked against the median, so
+// one quick repeat inside a real rhythm still counts.
+//
+// The other half of this is that hand-QA of the detector was unsafe: seeding a
+// pattern the obvious way, four chat turns in a row, poisoned the very pair
+// being tested.
+const MinIntervalDays = 2.0 / 24.0
+
 // Detect checks whether a sequence of events for the same action+object
 // forms a stable recurring pattern. Returns a ProposedRoutine when:
 //   - At least MinEvents events exist (≥3 intervals)
+//   - The median interval is at least MinIntervalDays
 //   - At least MinOnPatternFraction of the intervals sit within
 //     MaxIntervalRatio of the median interval
 //
@@ -88,8 +110,8 @@ func Detect(events []Event) (*ProposedRoutine, error) {
 	}
 
 	center := medianFloat(intervals)
-	if center <= 0 {
-		return nil, nil
+	if center <= 0 || center < MinIntervalDays {
+		return nil, nil // a burst, not a rhythm — see MinIntervalDays
 	}
 
 	// Keep the intervals that sit inside the band around the median. The