fix(java): Start jdtls with a bounded heap that returns memory to the OS (#210)

jdtls was launched with -Xms1G and no heap cap or GC choice, so the JVM grew to a quarter of physical RAM during import and kept it. Default VM args are now ParallelGC with GCTimeRatio/AdaptiveSizePolicyWeight, -Xmx2G -Xms100m, disabled memory-mapped zips and VM-install detection, prepended as --jvm-arg so both the direct and launcher-script paths get them. User JVM options replace the matching default (heap, -D/-XX by name, any -Xlog, any GC flag drops the whole GC group).

Fixes #193

Claude-Session: https://claude.ai/code/session_01Dq6jQQn8ZhRfkkyj3PRutA

src/platform/locales/text/zh.json

@@ -1328,7 +1328,7 @@
   "Passed as -Dmaven.repo.local.": "以 -Dmaven.repo.local 传入。",
   "Passed as -s (mirrors, servers, proxies).": "以 -s 传入（镜像、服务器、代理）。",
   "Passed to rustfmt when reformatting, e.g. --edition 2024": "重新格式化时传递给 rustfmt，例如 --edition 2024",
-  "Passed to the JVM running jdtls (java.jdt.ls.vmargs), e.g. -Xmx2g. A Lombok agent is added automatically: the one installed in Language Servers, else, when the project uses Lombok (its build, an inherited parent POM or Gradle build, or its sources' imports), the newest from the Maven / Gradle caches.": "传递给运行 jdtls 的 JVM (java.jdt.ls.vmargs)，例如 -Xmx2g。会自动添加 Lombok 代理：优先使用在“语言服务器”中安装的版本；否则当项目使用 Lombok（构建文件、继承的父 POM 或 Gradle 构建、源码中的 import）时，使用 Maven / Gradle 缓存中最新的版本。",
+  "Passed to the JVM running jdtls (java.jdt.ls.vmargs), e.g. -Xmx4g. jdtls runs with -XX:+UseParallelGC -XX:GCTimeRatio=4 -XX:AdaptiveSizePolicyWeight=90 -Xmx2G -Xms100m by default; an option set here replaces the default for the same setting, and another collector (e.g. -XX:+UseG1GC) replaces the default collector options. A Lombok agent is added automatically: the one installed in Language Servers, else, when the project uses Lombok (its build, an inherited parent POM or Gradle build, or its sources' imports), the newest from the Maven / Gradle caches.": "传递给运行 jdtls 的 JVM (java.jdt.ls.vmargs)，例如 -Xmx4g。jdtls 默认使用 -XX:+UseParallelGC -XX:GCTimeRatio=4 -XX:AdaptiveSizePolicyWeight=90 -Xmx2G -Xms100m 运行；此处设置的选项会替换同一设置的默认值，指定其他垃圾回收器（例如 -XX:+UseG1GC）时会替换默认的回收器选项。会自动添加 Lombok 代理：优先使用在“语言服务器”中安装的版本；否则当项目使用 Lombok（构建文件、继承的父 POM 或 Gradle 构建、源码中的 import）时，使用 Maven / Gradle 缓存中最新的版本。",
   "Pop stash": "弹出储藏",
   "Preview Source": "预览源代码",
   "Reinstate index": "恢复索引",