chore: clear non-code blockers ahead of the english-only cleanup (#1417)

- drop extensions/vscode/prototype.html: a UI design mock nothing in the
  codebase references, already excluded from the packaged extension
- register *.jar as binary now that gradle-wrapper.jar is tracked
- translate the Chinese comments in the IDEA plugin's gradle.properties

.gitattributes

@@ -5,4 +5,5 @@
 *.jpeg binary
 *.gif binary
 *.ico binary
+*.jar binary
 *.tiktoken binary

extensions/idea/gradle.properties

@@ -6,8 +6,12 @@ org.gradle.configuration-cache=true
 org.gradle.caching=true
 pluginVersion=0.3.0
 platformVersion=2025.1.4.1
-# 想用本机已安装的 IDEA 代替下载的平台包时，把 localIdePath 写进 ~/.gradle/gradle.properties，
-# 不要写在这里——它是机器相关的，提交后换操作系统就会构建失败。例如：
+# To build against a locally installed IDEA rather than the downloaded platform
+# archive, set localIdePath in ~/.gradle/gradle.properties — not here: the path is
+# machine-specific, so committing it breaks the build for anyone on another OS.
+# For example:
 #   macOS:   localIdePath=/Users/<you>/Applications/IntelliJ IDEA.app
 #   Windows: localIdePath=D:/Program Files/IntelliJ IDEA 2025.2.1
-# 注意：本机 IDEA 版本要和 platformVersion 同代，跨代（例如 2026.2）会因 Kotlin metadata 版本不兼容编译失败。
+# The local IDEA must be the same generation as platformVersion: crossing
+# generations (2026.2, say) fails to compile on an incompatible Kotlin metadata
+# version.

extensions/vscode/.vscodeignore

@@ -11,6 +11,5 @@ jest.config.js
 .eslintrc.json
 .vscode/**
 .superpowers/**
-prototype.html
 resources/icon-old.svg
 __mocks__/**