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

aster-core/examples/practical.ast

@@ -0,0 +1,209 @@
+// ============================================================================
+// 实用脚本集合：文本统计、数组工具、排序、数据转换
+// 运行: cargo run -- examples/practical.ast
+// ============================================================================
+
+// ============================================================================
+// 1. 文本统计工具
+// ============================================================================
+fn count_chars(s) {
+    return len(s)
+}
+
+fn count_words(s) {
+    let count = 0
+    let in_word = false
+    for (c in s) {
+        if (c == " " || c == "\n" || c == "\t") {
+            in_word = false
+        } else if (!in_word) {
+            count = count + 1
+            in_word = true
+        }
+    }
+    return count
+}
+
+fn text_stats(text) {
+    print("=== Text Stats ===")
+    print("chars:", count_chars(text))
+    print("words:", count_words(text))
+}
+
+let sample = "hello world from Aster scripting language"
+text_stats(sample)
+
+
+// ============================================================================
+// 2. 数组工具函数 (map / filter / reduce)
+// ============================================================================
+
+fn map(arr, func) {
+    let result = []
+    for (x in arr) {
+        push(result, func(x))
+    }
+    return result
+}
+
+fn filter(arr, pred) {
+    let result = []
+    for (x in arr) {
+        if (pred(x)) {
+            push(result, x)
+        }
+    }
+    return result
+}
+
+fn reduce(arr, func, init) {
+    let acc = init
+    for (x in arr) {
+        acc = func(acc, x)
+    }
+    return acc
+}
+
+let nums = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+
+let doubled = map(nums, fn(x) { return x * 2 })
+print("map (*2):", doubled)
+
+let evens = filter(nums, fn(x) { return x % 2 == 0 })
+print("filter (even):", evens)
+
+let sum = reduce(nums, fn(a, b) { return a + b }, 0)
+print("reduce (sum):", sum)
+
+// 链式: 偶数平方和
+let even_squares = map(
+    filter(nums, fn(x) { return x % 2 == 0 }),
+    fn(x) { return x * x }
+)
+let sum_squares = reduce(even_squares, fn(a, b) { return a + b }, 0)
+print("sum of even squares:", sum_squares)
+
+
+// ============================================================================
+// 3. 冒泡排序
+// ============================================================================
+
+fn sort(arr) {
+    let n = len(arr)
+    let i = 0
+    while (i < n - 1) {
+        let j = 0
+        while (j < n - i - 1) {
+            if (arr[j] > arr[j + 1]) {
+                let tmp = arr[j]
+                arr[j] = arr[j + 1]
+                arr[j + 1] = tmp
+            }
+            j = j + 1
+        }
+        i = i + 1
+    }
+    return arr
+}
+
+let unsorted = [42, 17, 8, 99, 3, 56]
+print("unsorted:", unsorted)
+print("sorted:", sort(unsorted))
+
+
+// ============================================================================
+// 4. 数据转换 (类 JSON 处理)
+// ============================================================================
+
+let users = [
+    { name: "Alice", age: 28, active: true },
+    { name: "Bob",   age: 35, active: false },
+    { name: "Carol", age: 22, active: true },
+    { name: "Dave",  age: 40, active: true },
+]
+
+// 找出活跃用户的名字，按年龄排序
+let active = filter(users, fn(u) { return u["active"] })
+print("active users:", len(active))
+
+// 计算平均年龄
+let total_age = reduce(users, fn(acc, u) { return acc + u["age"] }, 0)
+print("avg age:", total_age / len(users))
+
+// 生成名字列表
+let names = map(users, fn(u) { return u["name"] })
+print("names:", names)
+
+
+// ============================================================================
+// 5. 斐波那契 (递归 + 迭代 + 缓存对比)
+// ============================================================================
+
+fn fib_rec(n) {
+    if (n <= 1) { return n }
+    return fib_rec(n - 1) + fib_rec(n - 2)
+}
+
+fn fib_iter(n) {
+    if (n <= 1) { return n }
+    let a = 0
+    let b = 1
+    let i = 2
+    while (i <= n) {
+        let tmp = a + b
+        a = b
+        b = tmp
+        i = i + 1
+    }
+    return b
+}
+
+print("fib_rec(20):", fib_rec(20))
+print("fib_iter(20):", fib_iter(20))
+
+
+// ============================================================================
+// 6. 回文检测
+// ============================================================================
+
+fn is_palindrome(s) {
+    let n = len(s)
+    let i = 0
+    while (i < n / 2) {
+        if (s[i] != s[n - 1 - i]) {
+            return false
+        }
+        i = i + 1
+    }
+    return true
+}
+
+print("is_palindrome('radar'):", is_palindrome("radar"))
+print("is_palindrome('hello'):", is_palindrome("hello"))
+
+
+// ============================================================================
+// 7. 字符串工具（split / trim / substring / replace）
+// ============================================================================
+
+print("=== string utils ===")
+
+let csv = "Alice,Bob,Carol,Dave"
+let parts = split(csv, ",")
+print("split CSV:", parts)
+print("names count:", len(parts))
+
+let padded = "  hello  "
+print("trim:", "'" + trim(padded) + "'")
+
+print("substring('hello', 1, 3):", substring("hello", 1, 3))
+
+let template = "Hello, NAME!"
+let greeting = replace(template, "NAME", "Aster")
+print("replace:", greeting)
+
+print("contains('hello', 'ell'):", contains("hello", "ell"))
+print("upper:", upper("hello"))
+print("lower:", lower("HELLO"))
+print("starts_with('hello', 'he'):", starts_with("hello", "he"))
+print("ends_with('hello', 'lo'):", ends_with("hello", "lo"))