refactor: extract utility classes and split AppConfig

- CommandUtils: shared formatting (header, separator, formatBytes, formatDuration, progressBar, truncate)
- ToolValidator: input validation (requireString, getString, getInt, getBoolean, validatePathInWorkDir)
- ProcessExecutor: consolidated ProcessBuilder with timeout, cleanup, shell execution
- AbstractReadOnlyTool: base class for read-only tools
- Split AppConfig -> ToolConfiguration + CommandConfiguration + AppConfig (core)
- Applied CommandUtils to 16 command files, removed duplicated private methods
- Applied ToolValidator + ProcessExecutor to NotificationTool

Net: -403 lines removed, 87 tests still passing

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/java/com/claudecode/tool/util/ProcessExecutor.java

@@ -0,0 +1,115 @@
+package com.claudecode.tool.util;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.*;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * 进程执行器 —— 消除 BashTool、GrepTool、NotificationTool 中的重复 ProcessBuilder 模式。
+ * <p>
+ * 封装进程创建、超时管理、输出捕获和资源清理。
+ */
+public final class ProcessExecutor {
+
+    private ProcessExecutor() {}
+
+    /**
+     * 进程执行结果。
+     */
+    public record Result(int exitCode, String stdout, String stderr, boolean timedOut) {
+
+        public boolean isSuccess() {
+            return exitCode == 0 && !timedOut;
+        }
+
+        public String output() {
+            return stdout != null ? stdout : "";
+        }
+
+        public String combinedOutput() {
+            StringBuilder sb = new StringBuilder();
+            if (stdout != null && !stdout.isEmpty()) sb.append(stdout);
+            if (stderr != null && !stderr.isEmpty()) {
+                if (!sb.isEmpty()) sb.append("\n");
+                sb.append(stderr);
+            }
+            return sb.toString();
+        }
+    }
+
+    /**
+     * 在指定工作目录执行命令，带超时和资源清理。
+     */
+    public static Result execute(List<String> command, Path workDir, long timeoutMs) {
+        return execute(command, workDir, timeoutMs, null);
+    }
+
+    /**
+     * 在指定工作目录执行命令，带超时、环境变量和资源清理。
+     */
+    public static Result execute(List<String> command, Path workDir, long timeoutMs, Map<String, String> env) {
+        ProcessBuilder pb = new ProcessBuilder(command);
+        if (workDir != null) pb.directory(workDir.toFile());
+        pb.redirectErrorStream(false);
+
+        if (env != null && !env.isEmpty()) {
+            pb.environment().putAll(env);
+        }
+
+        Process process = null;
+        try {
+            process = pb.start();
+
+            String stdout;
+            String stderr;
+            try (var stdoutStream = process.getInputStream();
+                 var stderrStream = process.getErrorStream()) {
+                stdout = new String(stdoutStream.readAllBytes());
+                stderr = new String(stderrStream.readAllBytes());
+            }
+
+            boolean finished = process.waitFor(timeoutMs, TimeUnit.MILLISECONDS);
+            if (!finished) {
+                process.destroyForcibly();
+                process.waitFor(2, TimeUnit.SECONDS);
+                return new Result(-1, stdout, stderr, true);
+            }
+
+            return new Result(process.exitValue(), stdout, stderr, false);
+        } catch (IOException e) {
+            return new Result(-1, "", "IOException: " + e.getMessage(), false);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            return new Result(-1, "", "Interrupted", false);
+        } finally {
+            if (process != null && process.isAlive()) {
+                process.destroyForcibly();
+            }
+        }
+    }
+
+    /**
+     * 快速检查命令是否可用（which/where）。
+     */
+    public static boolean isCommandAvailable(String command) {
+        boolean isWindows = System.getProperty("os.name", "").toLowerCase().contains("win");
+        String checker = isWindows ? "where" : "which";
+        Result result = execute(List.of(checker, command), null, 5000);
+        return result.isSuccess();
+    }
+
+    /**
+     * 执行 shell 命令（通过 sh -c 或 cmd /c）。
+     */
+    public static Result executeShell(String shellCommand, Path workDir, long timeoutMs) {
+        boolean isWindows = System.getProperty("os.name", "").toLowerCase().contains("win");
+        List<String> command;
+        if (isWindows) {
+            command = List.of("cmd.exe", "/c", shellCommand);
+        } else {
+            command = List.of("/bin/sh", "-c", shellCommand);
+        }
+        return execute(command, workDir, timeoutMs);
+    }
+}