Add Apache 2.0 license header to all Pine Script files

Co-authored-by: mihakralj <31756078+mihakralj@users.noreply.github.com>

lib/core/avgprice/avgprice.pine

@@ -1,3 +1,5 @@
+// Licensed under the Apache License, Version 2.0
+// © mihakralj
 // AVGPRICE: Average Price
 // (Open + High + Low + Close) / 4
 // TA-Lib compatible — equivalent to TBar.OHLC4

lib/core/ha/ha.pine

@@ -1,3 +1,5 @@
+// Licensed under the Apache License, Version 2.0
+// © mihakralj
 // HA: Heikin-Ashi
 // Smoothed candle transformation with recursive open
 // HA_Close = (O + H + L + C) / 4

lib/core/medprice/medprice.pine

@@ -1,3 +1,5 @@
+// Licensed under the Apache License, Version 2.0
+// © mihakralj
 // MEDPRICE: Median Price
 // (High + Low) / 2
 // TA-Lib compatible — equivalent to TBar.HL2

lib/core/midpoint/midpoint.pine

@@ -1,3 +1,5 @@
+// Licensed under the Apache License, Version 2.0
+// © mihakralj
 // MIDPOINT: Rolling Midpoint
 // (Highest(source, N) + Lowest(source, N)) / 2
 // TA-Lib compatible — rolling center of value range

lib/core/midprice/midprice.pine

@@ -1,3 +1,5 @@
+// Licensed under the Apache License, Version 2.0
+// © mihakralj
 // MIDPRICE: Midpoint Price over Period
 // (Highest(High, N) + Lowest(Low, N)) / 2
 // TA-Lib compatible — center of the H/L price channel

lib/core/typprice/typprice.pine

@@ -1,3 +1,5 @@
+// Licensed under the Apache License, Version 2.0
+// © mihakralj
 // TYPPRICE: Typical Price
 // (High + Low + Close) / 3
 // TA-Lib compatible — equivalent to TBar.HLC3

lib/core/wclprice/wclprice.pine

@@ -1,3 +1,5 @@
+// Licensed under the Apache License, Version 2.0
+// © mihakralj
 // WCLPRICE: Weighted Close Price
 // (High + Low + 2 * Close) / 4
 // TA-Lib compatible — equivalent to TBar.HLCC4