feat(m175): Java 设置页接真运行时（扫描 / 手动路径 / 默认 JDK / 内存 / JVM 参数）

用户实测四条抱怨逐条对应：
- 「没有自动检测本机 Java」：首屏自动扫一次盘（托管根 + JAVA_HOME + PATH + 标准安装位置 +
  注册表），之后由「立即扫描」手动触发；扫描在后台线程里跑，带 done/total 进度与取消
- 「显示 Temurin 21.0.4 不知道是不是硬编码」：演示行与绊线测试一起删掉，列表来自真读盘
- 「没一个能改」：默认内存（MB，512~65536，范围与 schema 同源）与 JVM 参数可真改、真落盘、读回
- 「不能手动指定 Java 路径 / 不能改默认版本」：手动添加走严格校验（真跑 java -version），
  设为默认写 java.selected_path 并给出「为什么选它」（当前实例的版本门槛 + 每行满足与否）

core：java::manual（严格探测 + 厂商识别 + 名单持久化）、java::staged（候选收集 + 带进度与
取消的扫描）、java::proc（带超时且可打断的子进程执行：卡住的 java -version 会被 kill）。
i18n：catalog/settings/java.rs 55 条中英 + 金表按装配顺序插入。

复审 r1（p2-5items）全修：
- P2-1 「设为默认」不再清脏：只写 java.selected_path，内存/JVM 草稿一个字节都不动
- P2-2 错误文案全部走 i18n（三档「写不进去」/「路径太长」/「名单写不进去」各自一个 key），
  不再把 Rust 枚举名当人话
- P2-3 手动名单落盘有正面断言（加一条 → 从盘上新读一份 → 在）
- P2-4 版本号显示到小版本（17.0.13 / 17.0.9 可区分），解析不出来时给原始版本串
- P2-5 每候选 8 秒超时并 kill、取消打断正在跑的探测、扫描槽挂在 State 上、线程活着期间
  不许起第二个（界面显示「正在取消…」）

复审 r2（p2-2items）全修：
- P2-1 空态不再指向不存在的「Java 页」，改成真实存在的 `ull java install 21` 命令行入口
- P2-2 `auto_scan_due` 增加 `!report.cancelled`：取消过一次之后本进程不再自动扫，
  配置文件再变（存内存 / 改主题）也不会把取消无声撤销；手动「立即扫描」不受影响
- 顺带：proc 的 kill+wait 补「子进程真死了」的回归守卫（标记文件从未出现）、
  core 的 Schema 错误改成页面自己的 key（不再把中文 Display 直出给英文界面）、
  默认态 chip 用新的 `Chip::badge`（不再挂一条永远收不到的消息）

crates/i18n/src/catalog/golden/tail.rs

@@ -29,6 +29,65 @@ pub(super) const ROWS: &[(&str, &str, &str)] = &[
     ("SettingsAppearanceCornerSquare", "Square", "直角"),
     ("SettingsAppearanceCornerHint", "On Windows 11 and Server 2025 we ask the system for rounded corners; Windows 10 keeps square corners. On macOS and Linux the desktop's own rules apply. We never draw corners ourselves.", "Windows 11 与 Windows Server 2025 上我们请求系统处理外框圆角；Windows 10 保持直角；macOS 与 Linux 交给桌面合成器自己的规则；我们不自己画圆角。"),
     ("SettingsAppearanceCornerSuspended", "Not in effect right now: window transparency is below 100%. Setting it back to 100% restores the rounded corners.", "当前因整窗透明度不生效：把整窗透明度调回 100% 圆角即恢复。"),
+    // M175：设置页「Java」分组（`catalog/settings/java.rs` 的 `settings_java_entries`）。
+    // 位置就是装配链里那个域的位置：`settings_java_entries` 在 `settings_appearance_entries` 之后、
+    // `settings_download_entries`（空）与 `settings_ai_entries`（M174）之前，所以这几行必须落在
+    // `SettingsAppearanceCornerSuspended` 与 `SettingsGroupAssistant` 之间（顺序 = `Key::ALL`）。
+    ("SettingsJavaScan", "Scan now", "立即扫描"),
+    ("SettingsJavaScanningStart", "Scanning…", "正在扫描…"),
+    ("SettingsJavaScanning", "Scanning… {done}/{total}", "正在扫描… {done}/{total}"),
+    ("SettingsJavaCancelling", "Cancelling…", "正在取消…"),
+    ("SettingsJavaCancel", "Cancel", "取消"),
+    ("SettingsJavaCancelled", "The scan was cancelled; the list below is from the previous run.", "扫描已取消；下面的列表还是上一次的结果。"),
+    ("SettingsJavaScanDone", "{count} JDK found", "找到 {count} 个 JDK"),
+    ("SettingsJavaNeverScanned", "Not scanned yet", "还没扫描过"),
+    ("SettingsJavaNeverScannedBody", "Press Scan to look for installed JDKs (registry, common install folders, JAVA_HOME and PATH). Nothing runs until you do.", "点「立即扫描」去找已装的 JDK（注册表、常见安装目录、JAVA_HOME 与 PATH）。在那之前启动器不会自己去扫。"),
+    ("SettingsJavaEmptyTitle", "No Java runtime found", "未检测到 Java 运行时"),
+    ("SettingsJavaEmptyBody", "Nothing matched. Add the path of a JDK you already unpacked below, or install one with `ull java install 21` on the command line.", "没找到任何 JDK。可以在下面手动加上你自己解压的那份，或者用命令行 `ull java install 21` 装一个。"),
+    ("SettingsJavaDefault", "Default", "默认"),
+    ("SettingsJavaSetDefault", "Use as default", "设为默认"),
+    ("SettingsJavaFits", "Meets the current instance requirement", "满足当前实例的要求"),
+    ("SettingsJavaTooOld", "Below the requirement: this instance needs Java {minimum}+", "低于要求：当前实例需要 Java {minimum} 及以上"),
+    ("SettingsJavaDefaultSet", "Default JDK is now {path}", "默认 JDK 已设为 {path}"),
+    ("SettingsJavaSourceManaged", "installed by this launcher", "本启动器安装"),
+    ("SettingsJavaSourceEnv", "JAVA_HOME (environment variable)", "JAVA_HOME（环境变量）"),
+    ("SettingsJavaSourcePath", "on PATH", "PATH 上"),
+    ("SettingsJavaSourceSystem", "system install", "系统安装"),
+    ("SettingsJavaSourceManual", "added by you", "手动添加"),
+    ("SettingsJavaAdd", "Add a JDK path", "手动添加 JDK 路径"),
+    ("SettingsJavaAddPlaceholder", "C:\\Program Files\\Java\\jdk-21", "例：C:\\Program Files\\Java\\jdk-21"),
+    ("SettingsJavaAddHint", "A JDK folder or its java executable. We run `java -version` on it; anything that cannot answer is refused.", "JDK 目录或它的 java 可执行文件。会真跑一次 `java -version`；答不出话的一律拒绝。"),
+    ("SettingsJavaAddAction", "Add", "添加"),
+    ("SettingsJavaAdded", "Added {path}", "已添加 {path}"),
+    ("SettingsJavaMemory", "Default memory (MB)", "默认内存（MB）"),
+    ("SettingsJavaMemoryHint", "Whole megabytes, {min}–{max}. Instances without their own override follow this value.", "整数 MB，范围 {min}~{max}。没有实例级覆盖的实例都用它。"),
+    ("SettingsJavaLayerGlobal", "In effect: {mb} MB, from the global default.", "生效：{mb} MB，来自全局默认值。"),
+    ("SettingsJavaLayerInstance", "In effect: {mb} MB, set by instance {instance}. Changing the global value below will not affect that instance.", "生效：{mb} MB，由实例 {instance} 覆盖。改下面的全局值不会影响它。"),
+    ("SettingsJavaJvm", "Extra JVM arguments", "额外 JVM 参数"),
+    ("SettingsJavaJvmPlaceholder", "-XX:+UseG1GC -Dfile.encoding=UTF-8", "例：-XX:+UseG1GC -Dfile.encoding=UTF-8"),
+    ("SettingsJavaJvmHint", "Separated by spaces, quotes allowed. Appended to the command line of every launch; an instance's own JVM arguments come after it.", "按空白分隔，支持引号。会拼到每次启动的命令行上；实例自己的 JVM 参数排在它后面。"),
+    ("SettingsJavaJvmSaved", "Saved value: {value}", "已保存的值：{value}"),
+    ("SettingsJavaJvmSavedNone", "No extra JVM arguments are saved yet.", "还没有保存任何额外参数。"),
+    ("SettingsJavaSave", "Save", "保存"),
+    ("SettingsJavaSaved", "Saved and read back from disk. The next launch uses the new value.", "已保存，并从磁盘读回确认。下次启动就用新值。"),
+    ("SettingsJavaUnsaved", "There are unsaved changes.", "有未保存的改动。"),
+    ("SettingsJavaRefused", "Not saved: {reason}", "未保存：{reason}"),
+    ("SettingsJavaSkipNotDirty", "there was nothing to change, so no file was written", "没有任何改动，因此没有写文件"),
+    ("SettingsJavaSkipReadOnly", "the settings file is read-only: a newer launcher wrote it, or it is marked untrusted", "配置文件只读：它被更新版本的启动器写过，或被标记为不可信"),
+    ("SettingsJavaSkipUnreadable", "the settings file is untrusted, so it is treated as read-only", "配置文件不可信，因此按只读处理"),
+    ("SettingsJavaNoStorage", "No settings file is available in this run, so nothing can be scanned or saved.", "这一次运行没有可用的设置文件，扫描与保存都做不了。"),
+    ("SettingsJavaReasonMemoryEmpty", "the memory field is empty", "内存没填"),
+    ("SettingsJavaReasonMemoryNotNumber", "the memory must be a whole number of MB", "内存必须是整数 MB"),
+    ("SettingsJavaReasonMemoryRange", "the memory is outside the allowed range", "内存超出允许范围"),
+    ("SettingsJavaReasonJvmQuotes", "the JVM arguments have an unclosed quote", "JVM 参数里有没配对的引号"),
+    ("SettingsJavaReasonAddEmpty", "the path is empty", "路径是空的"),
+    ("SettingsJavaReasonAddMissing", "nothing exists at that path", "那个路径上什么都没有"),
+    ("SettingsJavaReasonAddNotJava", "there is no java executable at that path", "那个路径里没有 java 可执行文件"),
+    ("SettingsJavaReasonAddNoVersion", "java -version did not answer there, so it is not a usable JDK", "在那里跑不出 java -version，不是一份能用的 JDK"),
+    ("SettingsJavaReasonAddTooLong", "the path is too long to be a JDK location", "路径太长，不像是一个 JDK 位置"),
+    ("SettingsJavaReasonAddWriteFailed", "the JDK is fine, but the list file could not be written (disk or permission)", "这份 JDK 没问题，但名单文件写不进去（磁盘或权限）"),
+    ("SettingsJavaReasonAddDuplicate", "that JDK is already in the list", "这份 JDK 已经在列表里了"),
+    ("SettingsJavaReasonWriteFailed", "the settings file could not be written (disk full, no permission, or the value was rejected)", "设置写不进去（磁盘满、没权限，或这个值被拒绝）"),
     // M174：设置页「助手（AI）」分组（`catalog/settings/ai.rs` 的 `settings_ai_entries`）。
     // 位置就是装配链里那个域的位置：`settings_ai_entries` 在 `settings_download_entries` 之后、
     // `core_text_entries` 之前，所以这几行必须落在 `SettingsAppearanceCornerSuspended` 与