Update CHANGELOG for v1.2.1 and v1.2.0 improvements

Added details for v1.2.1, including performance optimizations, bug fixes, and new tests.

Author: lupodevelop

CHANGELOG.md

@@ -2,30 +2,37 @@
 
 All notable changes to this project are documented in this file.
 
-## [1.2.0] - 2025-12-20
-### Changed
-- `reverse/1` now uses the BEAM stdlib grapheme segmentation (`string.to_graphemes`) for better Unicode correctness and consistency across the library.
-
-### Performance
-- Optimized `count/3` internals to avoid repeated `list.length` calls inside recursive loops, improving performance on long strings.
-
-
-Contributed by: Daniele (`lupodevelop`)
-
 ## [1.2.1] - 2026-01-02
 ### Fixed
 - Made `repeat_str/2` iterative to avoid deep recursion and improve performance on large repetition counts.
 - Fixed `wrap_at/2` to measure word lengths using grapheme clusters to avoid splitting emoji and other multi-codepoint graphemes.
 - Replaced several `string.length(part) == 0` checks with `string.is_empty(part)` for clarity.
 
+### Performance
+- Optimized `find_common_prefix` to accept pre-segmented grapheme lists (`List(List(String))`) to avoid repeated `string.to_graphemes` conversions and expensive string concatenation/drop operations in recursive calls, reducing allocations and improving performance on lists of long strings (contributed by Miao `lemorage`).
+
+
 ### Tests
 - Added `wrap_at_emoji_grapheme_test` to verify grapheme-aware wrapping behavior.
 
 ### Style
 - Ran `gleam format` to normalize formatting.
 
+Contributed by: Daniele (`lupodevelop`), Miao (`lemorage`)
+
+## [1.2.0] - 2025-12-20
+### Changed
+- `reverse/1` now uses the BEAM stdlib grapheme segmentation (`string.to_graphemes`) for better Unicode correctness and consistency across the library.
+
+### Performance
+- Optimized `count/3` internals to avoid repeated `list.length` calls inside recursive loops, improving performance on long strings.
+
+### CI
+- Pinned Gleam version in CI and fixed build cache path/key for more reproducible and faster runs.
+
 Contributed by: Daniele (`lupodevelop`)
 
+
 ## [1.1.1] - 2025-11-30
 ### Fixed
 - Robustness fixes for grapheme-aware utilities; resolved parity issues in `ends_with/2` for complex ZWJ sequences.