Suppress subtitle annotations for grammar fragments

- Hide annotation metadata for auxiliary inflection and ja-nai endings
- Preserve lexical `くれる` forms and add regression coverage

changes/311-auxiliary-inflection-annotation-filter.md

@@ -0,0 +1,4 @@
+type: fixed
+area: overlay
+
+- Suppressed subtitle annotation styling for standalone auxiliary inflection fragments such as `れる` and `れた` while keeping lexical `くれる` forms eligible for lookup metadata.

changes/312-grammar-ending-annotation-filter.md

@@ -0,0 +1,4 @@
+type: fixed
+area: overlay
+
+- Suppressed subtitle annotation styling for grammar-only endings such as `じゃないですか` and standalone polite copula tails like `です` / `ですよ`.