test(snap): add nested-oxc-config-proj-1 to reproduce nested vite.config.ts loading bug

Mirrors the layout from oxc-project/oxc#20416: a root `vite.config.ts`
plus `packages/proj-1/vite.config.ts`. Running `vp lint` / `vp fmt`
from `packages/proj-1` should pick up the nested config, but the
committed snap shows both commands exit with [1] applying the root
config instead (root `no-debugger: error` vs proj-1 `off`, root
`singleQuote: true` vs proj-1 `false`).

Refs oxc-project/oxc#20416

Author: fengmk2

packages/cli/snap-tests/nested-oxc-config-proj-1/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "nested-oxc-config-proj-1-test",
+  "version": "0.0.0",
+  "private": true,
+  "type": "module",
+  "packageManager": "pnpm@10.16.1"
+}

packages/cli/snap-tests/nested-oxc-config-proj-1/packages/proj-1/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "proj-1",
+  "version": "0.0.0",
+  "private": true
+}

packages/cli/snap-tests/nested-oxc-config-proj-1/packages/proj-1/src/index.js

@@ -0,0 +1,6 @@
+function hello() {
+  debugger;
+  return 'hello from proj-1';
+}
+
+export { hello };

packages/cli/snap-tests/nested-oxc-config-proj-1/packages/proj-1/vite.config.ts

@@ -0,0 +1,13 @@
+// Nested proj-1 config: relaxes the root's strict rules.
+// Running `vp lint` / `vp fmt` from packages/proj-1 should pick this up
+// (matching oxc-project/oxc#20416), but currently the root config is used instead.
+export default {
+  lint: {
+    rules: {
+      'no-debugger': 'off',
+    },
+  },
+  fmt: {
+    singleQuote: false,
+  },
+};

packages/cli/snap-tests/nested-oxc-config-proj-1/pnpm-lock.yaml

@@ -0,0 +1,2 @@
+packages:
+  - 'packages/*'

packages/cli/snap-tests/nested-oxc-config-proj-1/pnpm-workspace.yaml

@@ -0,0 +1,25 @@
+> # Reproduces oxc-project/oxc#20416: nested vite.config.ts in packages/proj-1
+> # should override root config when `vp lint` / `vp fmt` run from that cwd.
+> # proj-1 disables no-debugger and turns off singleQuote, so both commands
+> # should pass. If the root config leaks through, lint reports a debugger
+> # violation and fmt reports a quote-style diff.
+[1]> cd packages/proj-1 && vp lint # expected: pass (proj-1 disables no-debugger); actual: fails with root rule
+
+  × eslint(no-debugger): `debugger` statement is not allowed
+   ╭─[src/index.js:2:3]
+ 1 │ function hello() {
+ 2 │   debugger;
+   ·   ─────────
+ 3 │   return "hello from proj-1";
+   ╰────
+  help: Remove the debugger statement
+
+Found 0 warnings and 1 error.
+Finished in <variable>ms on 2 files with <variable> rules using <variable> threads.
+
+[1]> cd packages/proj-1 && vp fmt --check # expected: pass (proj-1 sets singleQuote:false); actual: fails with root singleQuote:true
+Checking formatting...
+src/index.js (<variable>ms)
+
+Format issues found in above 1 files. Run without `--check` to fix.
+Finished in <variable>ms on 3 files using <variable> threads.

packages/cli/snap-tests/nested-oxc-config-proj-1/snap.txt

@@ -0,0 +1,12 @@
+{
+  "ignoredPlatforms": ["win32"],
+  "commands": [
+    "# Reproduces oxc-project/oxc#20416: nested vite.config.ts in packages/proj-1",
+    "# should override root config when `vp lint` / `vp fmt` run from that cwd.",
+    "# proj-1 disables no-debugger and turns off singleQuote, so both commands",
+    "# should pass. If the root config leaks through, lint reports a debugger",
+    "# violation and fmt reports a quote-style diff.",
+    "cd packages/proj-1 && vp lint # expected: pass (proj-1 disables no-debugger); actual: fails with root rule",
+    "cd packages/proj-1 && vp fmt --check # expected: pass (proj-1 sets singleQuote:false); actual: fails with root singleQuote:true"
+  ]
+}

packages/cli/snap-tests/nested-oxc-config-proj-1/steps.json

@@ -0,0 +1,12 @@
+// Root config: strict rules that should NOT apply when running from packages/proj-1.
+// If proj-1's nested vite.config.ts is loaded correctly, these rules are overridden.
+export default {
+  lint: {
+    rules: {
+      'no-debugger': 'error',
+    },
+  },
+  fmt: {
+    singleQuote: true,
+  },
+};