chore: remove shipped changelog entries and demo asset

- Drop changes/kiku-field-grouping-modal-wiring.md (landed in #138)
- Drop changes/known-word-partial-reading-highlight.md (landed in #142)
- Remove assets/minecard.mkv demo video

changes/kiku-field-grouping-modal-wiring.md

@@ -1,4 +0,0 @@
-type: fixed
-area: overlay
-
-- Fixed the Kiku field grouping modal misbehaving on Hyprland/Wayland while every other modal worked: its main-process wiring silently dropped the modal-open acknowledgement/retry, failure teardown, and warn-logging callbacks (they are optional, so the incomplete forward compiled cleanly), and it skipped the overlay prerequisites every other modal runs before opening. The field grouping modal now opens through the same path as the other modals — preparing the overlay runtime and visible overlay window first, then acknowledging/retrying the dedicated modal window — so it appears above and works over fullscreen mpv like the rest.

changes/known-word-partial-reading-highlight.md

@@ -1,4 +0,0 @@
-type: fixed
-area: overlay
-
-- Fixed never-mined compound words (e.g. 待ち合わせてる) being highlighted green as known: subtitle tokens now carry complete readings instead of kanji-only furigana joins, and the known-word reading fallback rejects readings that don't cover the token surface. Stored word readings in the stats database are no longer truncated for new lines.