Yahoo KeyKey 2 v2.10.0

What's Changed

• fix(engine): report and set aside an unreadable user-frequency store by @teddychan in #76
• chore(packages): enable complete concurrency checking as warnings by @teddychan in #77
• fix(app): guard the whole Cangjie table set with one lock by @teddychan in #78
• feat(a11y): expose the candidate window to assistive technologies by @teddychan in #79
• refactor(input): extract pure key-routing decisions and cover them with tests by @teddychan in #80
• perf(build): compile release builds with -O by @teddychan in #81
• ci: fail the build on compiler warnings by @teddychan in #82
• feat(deps): adopt DragonKit v2.4.0 by @teddychan in #83
• docs(release): prepare the 2.10.0 release notes by @teddychan in #84

Full Changelog: v2.9.1...v2.10.0