feat: command layer enhancements (Phase 1B.3)

- /help: keyword search + command detail view
- /compact: --stats for token statistics, --aggressive for deeper compaction
- /commit: --push to push after commit, --pr to create PR via gh CLI
- /files: directory tree with depth control, file pattern search
- /permissions: view current permission mode and rules
- /tasks: list background tasks with status, age, result preview

Total commands: 28 → 31

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

src/main/java/com/claudecode/command/impl/HelpCommand.java

@@ -5,9 +5,17 @@ import com.claudecode.command.SlashCommand;
 import com.claudecode.console.AnsiStyle;
 
 import java.util.List;
+import java.util.stream.Collectors;
 
 /**
  * /help 命令 —— 动态展示所有已注册的斜杠命令。
+ * <p>
+ * 支持：
+ * <ul>
+ *   <li>/help —— 列出所有命令</li>
+ *   <li>/help [keyword] —— 搜索匹配的命令</li>
+ *   <li>/help [command] —— 显示特定命令详情</li>
+ * </ul>
  */
 public class HelpCommand implements SlashCommand {
 
@@ -18,7 +26,7 @@ public class HelpCommand implements SlashCommand {
 
     @Override
     public String description() {
-        return "Show available commands";
+        return "Show available commands. Use /help [keyword] to search or /help [command] for details.";
     }
 
     @Override
@@ -28,13 +36,52 @@ public class HelpCommand implements SlashCommand {
 
     @Override
     public String execute(String args, CommandContext context) {
+        String query = (args == null) ? "" : args.strip();
+        var allCommands = context.commandRegistry().getCommands();
+
+        // If a specific command name is given, show details
+        if (!query.isEmpty()) {
+            String queryClean = query.startsWith("/") ? query.substring(1) : query;
+
+            // Exact match → show detail
+            var exactMatch = allCommands.stream()
+                    .filter(cmd -> cmd.name().equalsIgnoreCase(queryClean)
+                            || cmd.aliases().stream().anyMatch(a -> a.equalsIgnoreCase(queryClean)))
+                    .findFirst();
+
+            if (exactMatch.isPresent()) {
+                return formatCommandDetail(exactMatch.get());
+            }
+
+            // Fuzzy search by keyword
+            String queryLower = queryClean.toLowerCase();
+            var matches = allCommands.stream()
+                    .filter(cmd -> cmd.name().toLowerCase().contains(queryLower)
+                            || cmd.description().toLowerCase().contains(queryLower))
+                    .collect(Collectors.toList());
+
+            if (matches.isEmpty()) {
+                return AnsiStyle.yellow("  No commands matching \"" + query + "\"\n")
+                        + AnsiStyle.dim("  Use /help to see all commands");
+            }
+
+            StringBuilder sb = new StringBuilder();
+            sb.append(AnsiStyle.bold("\n  Commands matching \"" + query + "\":\n\n"));
+            appendCommandList(sb, matches);
+            return sb.toString();
+        }
+
+        // No args → show all
         StringBuilder sb = new StringBuilder();
         sb.append(AnsiStyle.bold("\n  Available Commands:\n\n"));
+        appendCommandList(sb, allCommands);
+        sb.append("\n");
+        sb.append(AnsiStyle.dim("  💡 Use /help [command] for details, /help [keyword] to search\n"));
+        sb.append(AnsiStyle.dim("  Shortcuts: Tab to autocomplete, ↑↓ to browse history, Ctrl+D to exit\n"));
+        return sb.toString();
+    }
 
-        // 从 CommandRegistry 动态获取所有已注册命令
-        var commands = context.commandRegistry().getCommands();
-
-        // 计算最长命令名称用于对齐
+    private void appendCommandList(StringBuilder sb, List<? extends SlashCommand> commands) {
         int maxNameLen = commands.stream()
                 .mapToInt(cmd -> cmd.name().length())
                 .max().orElse(12);
@@ -42,7 +89,6 @@ public class HelpCommand implements SlashCommand {
 
         for (SlashCommand cmd : commands) {
             String nameStr = "/" + cmd.name();
-            // 如果有别名，附加显示
             String aliasStr = "";
             if (!cmd.aliases().isEmpty()) {
                 aliasStr = AnsiStyle.DIM + " (also: "
@@ -52,10 +98,17 @@ public class HelpCommand implements SlashCommand {
             sb.append(String.format("  %s%-" + (maxNameLen + 2) + "s%s %s%s%n",
                     AnsiStyle.CYAN, nameStr, AnsiStyle.RESET, cmd.description(), aliasStr));
         }
+    }
 
-        sb.append("\n");
-        sb.append(AnsiStyle.dim("  Shortcuts: Tab to autocomplete, ↑↓ to browse history, Ctrl+D to exit\n"));
-
+    private String formatCommandDetail(SlashCommand cmd) {
+        StringBuilder sb = new StringBuilder();
+        sb.append("\n  ").append(AnsiStyle.bold("/" + cmd.name())).append("\n");
+        sb.append("  ").append("─".repeat(40)).append("\n");
+        sb.append("  ").append(cmd.description()).append("\n");
+        if (!cmd.aliases().isEmpty()) {
+            sb.append("  ").append(AnsiStyle.dim("Aliases: "
+                    + cmd.aliases().stream().map(a -> "/" + a).collect(Collectors.joining(", ")))).append("\n");
+        }
         return sb.toString();
     }
 }