v0.2.1

Fixed

• harmonicMean() — calling
  harmonicMean(DeciContext.CURRENCY_USD) on large values (e.g., 1200) caused a
  DeciDivisionByZeroException because reciprocals like 1/1200 rounded to 0.00
  at 2 decimal places. Intermediate reciprocal calculations now use extra internal
  precision (context.precision + 10), matching the pattern already used by sqrt().

Changed

• Sample app restructured into a 5-tab navigation app (Core, Scale & Context,
  Financial, Format & Stats, Validation) showcasing all library features.

• toString() now preserves trailing zeros — Deci("1.50").toString() returns
  "1.50", and Deci("1.2300").toString() returns "1.2300". The JVM/Android
  constructor no longer strips trailing zeros.

• toString() never uses scientific notation — guaranteed across all platforms
  (JVM, Android, JS, wasmJs, Apple). For example, Deci("100000000000000000000").toString()
  always returns "100000000000000000000", never "1E+20".