feat: IDE支持 — workspace拆分、LSP服务器、VS Code扩展

**Workspace 拆分**
- aster-core: 纯库，zero-dependency，包含 lexer/parser/ast/interpreter/error/analysis
- aster: REPL 二进制，薄封装 aster-core
- aster-lsp: LSP 语言服务器

**VS Code 扩展 (vscode-ext/)**
- TextMate 语法高亮 (.ast 文件)
- 语言配置 (注释切换、括号配对、自动缩进)
- LSP 客户端 (extension.js)

**LSP 服务端功能**
- Diagnostics: 实时显示 lex/parse 错误红色波浪线
- Completion: 关键字 + 内置函数 + 用户定义符号补全
- Hover: 悬停显示变量/函数信息
- Signature Help: 函数参数提示
- Goto Definition: Ctrl+Click 跳转到声明处
- Find References: 查找所有引用位置
- Rename: F2 重命名符号

**新增 analysis 模块**
- collect_symbols: AST 遍历收集符号
- find_declaration/find_all_references: Token 扫描定位声明和引用

vscode-ext/package.json

@@ -0,0 +1,39 @@
+{
+    "name": "aster-lang",
+    "displayName": "Aster Language Support",
+    "description": "Syntax highlighting and language support for the Aster scripting language",
+    "version": "0.1.0",
+    "publisher": "aster",
+    "engines": {
+        "vscode": "^1.85.0"
+    },
+    "categories": [
+        "Programming Languages"
+    ],
+    "main": "./extension.js",
+    "contributes": {
+        "languages": [
+            {
+                "id": "aster",
+                "aliases": [
+                    "Aster",
+                    "aster"
+                ],
+                "extensions": [
+                    ".ast"
+                ],
+                "configuration": "./language-configuration.json"
+            }
+        ],
+        "grammars": [
+            {
+                "language": "aster",
+                "scopeName": "source.aster",
+                "path": "./syntaxes/aster.tmLanguage.json"
+            }
+        ]
+    },
+    "dependencies": {
+        "vscode-languageclient": "^9.0.0"
+    }
+}