feat: Phase1 项目骨架 - Maven项目结构、核心AgentLoop、6个工具、命令系统、控制台渲染、REPL会话

实现内容:
- pom.xml: JDK25 + Spring AI 2.0.0-M4 + JLine3 + Picocli
- core/AgentLoop: 基于ChatModel的显式工具循环（非ChatClient）
- tool/: Tool接口 + ToolRegistry + ToolCallbackAdapter（适配Spring AI）
- tool/impl/: BashTool, FileReadTool, FileWriteTool, FileEditTool, GlobTool, GrepTool
- command/: SlashCommand接口 + CommandRegistry + /help, /clear, /exit
- console/: AnsiStyle, BannerPrinter, ToolStatusRenderer, ThinkingRenderer, SpinnerAnimation, MarkdownRenderer
- context/: SystemPromptBuilder, ClaudeMdLoader（多级CLAUDE.md加载）
- repl/ReplSession: REPL主循环（Scanner降级方案）
- config/AppConfig: Spring Bean装配
- application.yml: Anthropic/OpenAI双模型配置

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

src/main/java/com/claudecode/context/SystemPromptBuilder.java

@@ -0,0 +1,83 @@
+package com.claudecode.context;
+
+/**
+ * 系统提示词构建器 —— 对应 claude-code/src/prompts.ts。
+ * <p>
+ * 组装完整的系统提示词，包括核心指令、环境信息、工具说明等。
+ */
+public class SystemPromptBuilder {
+
+    private String workDir;
+    private String osName;
+    private String userName;
+    private String claudeMdContent;
+    private String customInstructions;
+
+    public SystemPromptBuilder() {
+        this.workDir = System.getProperty("user.dir");
+        this.osName = System.getProperty("os.name");
+        this.userName = System.getProperty("user.name");
+    }
+
+    public SystemPromptBuilder workDir(String workDir) {
+        this.workDir = workDir;
+        return this;
+    }
+
+    public SystemPromptBuilder claudeMd(String content) {
+        this.claudeMdContent = content;
+        return this;
+    }
+
+    public SystemPromptBuilder customInstructions(String instructions) {
+        this.customInstructions = instructions;
+        return this;
+    }
+
+    /**
+     * 构建完整的系统提示词。
+     */
+    public String build() {
+        StringBuilder sb = new StringBuilder();
+
+        // 核心角色定义
+        sb.append("""
+                You are Claude, an AI assistant made by Anthropic, operating as a CLI coding agent.
+                You are an interactive CLI tool that helps users with software engineering tasks.
+                Use the provided tools to help the user with their request.
+
+                """);
+
+        // 环境信息
+        sb.append("# Environment\n");
+        sb.append("- Working directory: ").append(workDir).append("\n");
+        sb.append("- OS: ").append(osName).append("\n");
+        sb.append("- User: ").append(userName).append("\n");
+        sb.append("\n");
+
+        // 行为准则
+        sb.append("""
+                # Guidelines
+                - Be concise in responses, but thorough in implementation
+                - Always verify changes work before considering a task done
+                - Use tools to explore the codebase before making changes
+                - When writing code, follow existing patterns and conventions
+                - Ask for clarification when requirements are ambiguous
+                
+                """);
+
+        // CLAUDE.md 内容
+        if (claudeMdContent != null && !claudeMdContent.isBlank()) {
+            sb.append("# Project Instructions (CLAUDE.md)\n");
+            sb.append(claudeMdContent).append("\n\n");
+        }
+
+        // 自定义指令
+        if (customInstructions != null && !customInstructions.isBlank()) {
+            sb.append("# Custom Instructions\n");
+            sb.append(customInstructions).append("\n\n");
+        }
+
+        return sb.toString();
+    }
+}