fix(parser): preserve legal comments with @preserve/@license when preceded by other annotations (#15929)

Legal comments like `/* @foo @preserve */` were not being preserved when legal comment output was enabled. The parser only checked if the first `@` annotation matched known patterns, missing `@preserve`/`@license` later in the comment.

## Changes

**Parser (`oxc_parser/src/lexer/trivia_builder.rs`)**
- Add fallback check using `contains_license_or_preserve_comment` after `__PURE__`/`__NO_SIDE_EFFECTS__` checks
- Ensures `@license`/`@preserve` detected anywhere in comment text

## Example

```javascript
// Before: Legal comment not detected by parser
/* @foo @preserve */ function foo() {}
// Parser classifies as: CommentContent::None ❌

// After: Legal comment correctly detected
/* @foo @preserve */ function foo() {}
// Parser classifies as: CommentContent::Legal ✅
```

Related: rolldown/rolldown#7160

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<details>

<summary>Original prompt</summary>

> `/* @foo @preserve */` should be preserved when legal comment output is enabled even if comment output is disabled. rolldown/rolldown#7160 is related

</details>

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Author: Copilot

crates/oxc_parser/src/lexer/trivia_builder.rs

@@ -248,11 +248,19 @@ impl TriviaBuilder {
             if rest.starts_with(b"PURE__") {
                 comment.content = CommentContent::Pure;
                 self.has_pure_comment = true;
+                return;
             } else if rest.starts_with(b"NO_SIDE_EFFECTS__") {
                 comment.content = CommentContent::NoSideEffects;
                 self.has_no_side_effects_comment = true;
+                return;
             }
         }
+
+        // Fallback: check for @license or @preserve anywhere in the comment
+        // This handles cases like /* @foo @preserve */ where the first @ doesn't match known patterns
+        if contains_license_or_preserve_comment(s) {
+            comment.content = CommentContent::Legal;
+        }
     }
 }
 
@@ -504,6 +512,8 @@ token /* Trailing 1 */
             ("/* @license */", CommentContent::Legal),
             ("/* foo @preserve */", CommentContent::Legal),
             ("/* foo @license */", CommentContent::Legal),
+            ("/* @foo @preserve */", CommentContent::Legal),
+            ("/* @foo @license */", CommentContent::Legal),
             ("/** foo @preserve */", CommentContent::JsdocLegal),
             ("/** foo @license */", CommentContent::JsdocLegal),
             ("/** jsdoc */", CommentContent::Jsdoc),