fix(coverage): match Babel's options.json inheritance for test fixtures (#19002)

## Summary

- Fix Babel test fixture options.json inheritance to match `@babel/helper-fixtures` behavior
- Babel's hierarchy: task → suite → category. Suite options.json REPLACES (not merges) category plugins
- Previously `expect-plugin` tests incorrectly inherited TypeScript plugin from parent category
- Fixes 3 tests: `export-interface`, `export-type`, `export-type-named`

**Results:** Negative Passed improved from 1660/1689 (98.28%) to 1663/1689 (98.46%)

🤖 Generated with [Claude Code](https://claude.ai/code)

crates/oxc_transformer/src/options/babel/mod.rs

@@ -117,28 +117,39 @@ fn default_as_true() -> bool {
 
 impl BabelOptions {
     /// Read options.json and merge them with options.json from ancestors directories.
+    ///
+    /// Babel's fixture hierarchy: task → suite → category.
+    /// Suite options.json REPLACES category plugins (not merge).
+    ///
     /// # Panics
     pub fn from_test_path(path: &Path) -> Self {
         let mut babel_options: Option<Self> = None;
         let mut plugins_json = None;
         let mut presets_json = None;
+        // Track if suite level (level 1) has options.json - if so, skip category plugins
+        let mut suite_has_options = false;
 
-        for path in path.ancestors().take(3) {
+        for (level, path) in path.ancestors().take(3).enumerate() {
             let file = path.join("options.json");
             if !file.exists() {
                 continue;
             }
 
+            if level == 1 {
+                suite_has_options = true;
+            }
+
             let content = std::fs::read_to_string(&file).unwrap();
             let mut new_value = serde_json::from_str::<serde_json::Value>(&content).unwrap();
 
             let new_plugins = new_value.as_object_mut().unwrap().remove("plugins");
-            if plugins_json.is_none() {
+            // Skip category (level 2) plugins if suite (level 1) has options.json
+            if plugins_json.is_none() && !(level == 2 && suite_has_options) {
                 plugins_json = new_plugins;
             }
 
             let new_presets = new_value.as_object_mut().unwrap().remove("presets");
-            if presets_json.is_none() {
+            if presets_json.is_none() && !(level == 2 && suite_has_options) {
                 presets_json = new_presets;
             }
 

tasks/coverage/snapshots/parser_babel.snap

@@ -3,7 +3,7 @@ commit: 92c052dc
 parser_babel Summary:
 AST Parsed     : 2224/2224 (100.00%)
 Positive Passed: 2211/2224 (99.42%)
-Negative Passed: 1665/1689 (98.58%)
+Negative Passed: 1668/1689 (98.76%)
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/es2026/explicit-resource-management/invalid-for-using-of-no-initializer/input.js
 
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/cast/unparenthesized-assert-and-assign/input.ts
@@ -34,12 +34,6 @@ Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/ty
 
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/dts/invalid-class-initializer/input.ts
 
-Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/expect-plugin/export-interface/input.js
-
-Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/expect-plugin/export-type/input.js
-
-Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/expect-plugin/export-type-named/input.js
-
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/export/equals-in-script/input.ts
 
 Expect Syntax Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/import/equals-in-script/input.ts
@@ -13208,6 +13202,25 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Try inserting a semicolon here
 
+  × Unexpected token
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/expect-plugin/export-interface/input.js:1:8]
+ 1 │ export interface Foo {}
+   ·        ─────────
+   ╰────
+
+  × Unexpected token
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/expect-plugin/export-type/input.js:1:8]
+ 1 │ export type Foo = number;
+   ·        ────
+   ╰────
+
+  × Unexpected token
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/expect-plugin/export-type-named/input.js:2:8]
+ 1 │ var Foo;
+ 2 │ export type { Foo };
+   ·        ────
+   ╰────
+
   × Unexpected exponentiation expression
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/exponentiation/await-non-null-before-exponential/input.ts:1:14]
  1 │ async (a) => await a! ** 6;