docs(changelog): finalize 1.6.1 release notes

Document the B&W filter (#221), always-show OCR toggle (#220), and the Firefox import storage fix (#223) under 1.6.1.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Gnathonic

CHANGELOG.md

@@ -1,9 +1,15 @@
 # Changelog
 
-## [1.6.1] - 2026-05-30
+## [1.6.1] - 2026-06-08
+
+### Added
+
+- Black & white (grayscale) filter with G hotkey (#221)
+- "Always show OCR" toggle with T shortcut (#220, @jakobnator)
 
 ### Fixed
 
+- Firefox now requests storage upfront so imports succeed (#223)
 - Achievement badges stay consistent across themes
 
 ## [1.6.0] - 2026-05-29