fix: Lexer 支持 -- 行注释和块注释，修复演示页解析报错

src/sql/lexer.ts

@@ -85,6 +85,16 @@ export class Lexer {
         tok = { type: TokenType.EOF, value: '', position: this.position };
         break;
       default:
+        // SQL 注释: -- 行注释
+        if (this.ch === '-' && this.peekChar() === '-') {
+          this.skipLineComment();
+          return this.nextToken();
+        }
+        // SQL 注释: /* 块注释 */
+        if (this.ch === '/' && this.peekChar() === '*') {
+          this.skipBlockComment();
+          return this.nextToken();
+        }
         if (this.isLetter(this.ch)) {
           const ident = this.readIdentifier();
           const keyword = KEYWORDS[ident.toUpperCase()];
@@ -135,6 +145,26 @@ export class Lexer {
     }
   }
 
+  /** 跳过 -- 行注释到行尾 */
+  private skipLineComment(): void {
+    while (this.ch !== '\n' && this.ch !== '\r' && this.ch !== '') {
+      this.readChar();
+    }
+  }
+
+  /** 跳过块注释 slash-star ... star-slash */
+  private skipBlockComment(): void {
+    this.readChar(); // skip *
+    this.readChar(); // move past *
+    while (this.ch !== '' && !(this.ch === '*' && this.peekChar() === '/')) {
+      this.readChar();
+    }
+    if (this.ch !== '') {
+      this.readChar(); // skip *
+      this.readChar(); // skip /
+    }
+  }
+
   private readIdentifier(): string {
     const start = this.position;
     while (this.isLetter(this.ch) || this.isDigit(this.ch) || this.ch === '_') {