feat(09-02): update autoAssignFreq range to [2500, 4000] Hz

- Change baseHz from 1200.0 to 2500.0
- Change numSteps from uint32(24) to uint32(31)
- Update function comment to reflect new range
- Prevents collision with built-in frequencies (max 2449 Hz)

config/config.go

@@ -205,15 +205,15 @@ func convertRules(raw []RawRule) []classify.Rule {
 	return result
 }
 
-// autoAssignFreq computes a deterministic frequency in [1200, 2350] Hz for a class name
+// autoAssignFreq computes a deterministic frequency in [2500, 4000] Hz for a class name
 // using FNV-32a hashing. Same input always produces the same output.
 func autoAssignFreq(className string) float64 {
 	h := fnv.New32a()
 	h.Write([]byte(className))
 	const (
-		baseHz   = 1200.0
+		baseHz   = 2500.0
 		stepHz   = 50.0
-		numSteps = uint32(24)
+		numSteps = uint32(31) // [2500, 4000] Hz in 50 Hz steps
 	)
 	return baseHz + float64(h.Sum32()%numSteps)*stepHz
 }