feat(stats): add Hide Kana filter and fix vocabulary exclusion matching

- Remove overlay mining image toast; OSD card notifications no longer flash a frame screenshot
- Add Hide Kana toggle to frequency rank table to filter kana-only headwords
- Fix vocab exclusions to deduplicate and match token variants (e.g. ない / 無い) under one exclusion entry
- Skip cover image fetching when the overview tab is inactive

changes/fix-stats-vocab-exclusions.md

@@ -0,0 +1,4 @@
+type: fixed
+area: stats
+
+- Fixed vocabulary exclusions so adding a word once hides matching token variants across the vocabulary page and duplicate exclusions are collapsed.

changes/overlay-mining-image-toast.md

@@ -1,4 +0,0 @@
-type: added
-area: overlay
-
-- Show a screenshot of the mined frame as an in-overlay image toast alongside the OSD card-mining notification, matching the picture already shown on system notifications.

changes/stats-hide-kana-filter.md

@@ -0,0 +1,4 @@
+type: added
+area: stats
+
+- Added a Hide Kana filter to the common-words frequency table so kana-only headwords can be hidden while reviewing mining targets.