chore(#1328): remove orphaned root vitest.config.ts left by SDK retirement

vitest.config.ts configured Vitest (not a dependency) to run .ts test files (the repo has none) rooted at ./sdk, a directory deleted when the SDK package seam was retired in #191 (ADR-0174). No npm script, workflow, or dependency references it.

Also drop the now-dead sdk/src/*.test.* branch in diff-touches-shipped-paths.cjs isCiGating(), which can never match since the sdk/ tree no longer exists.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/diff-touches-shipped-paths.cjs

@@ -12,11 +12,10 @@
  *   - package.json (always included by `npm pack`, regardless of `files`)
  *   - every entry in package.json `files`, treated as either an exact
  *     file match or a directory prefix (matching `npm pack` semantics).
- *   - CI-gating test paths: `tests/<anything>` plus
- *     `sdk/src/<anything>/<name>.test.<ts|cjs|mjs|js>` and `.spec.` variants
- *     — these don't ship in the tarball, but they gate the hotfix-branch
- *     test job. A test fixture update that aligns with a cherry-picked
- *     production fix MUST be pickable or CI fails on the hotfix run.
+ *   - CI-gating test paths: `tests/<anything>` — these don't ship in the
+ *     tarball, but they gate the hotfix-branch test job. A test fixture
+ *     update that aligns with a cherry-picked production fix MUST be
+ *     pickable or CI fails on the hotfix run.
  *     #3621 — root cause of the v1.42.3 hotfix red CI.
  *
  * `package-lock.json` is intentionally NOT considered shipped — `npm pack`
@@ -65,12 +64,7 @@ function loadShipPrefixes(pkgPath) {
 // in hotfix.yml, this lets `test(####):` fixture-alignment commits be
 // cherry-picked alongside their production counterparts.
 function isCiGating(diffPath) {
-  if (diffPath.startsWith('tests/')) return true;
-  // SDK vitest specs live next to source. Production source ships via
-  // sdk/dist/ (already in package.json `files`); the test files are what's
-  // missing from that surface.
-  if (diffPath.startsWith('sdk/src/') && /\.(test|spec)\.(ts|cjs|mjs|js)$/.test(diffPath)) return true;
-  return false;
+  return diffPath.startsWith('tests/');
 }
 
 function isShipped(diffPath, shipPrefixes) {

vitest.config.ts

@@ -1,24 +0,0 @@
-import { defineConfig } from 'vitest/config';
-
-export default defineConfig({
-  test: {
-    projects: [
-      {
-        test: {
-          name: 'unit',
-          root: './sdk',
-          include: ['src/**/*.test.ts'],
-          exclude: ['src/**/*.integration.test.ts'],
-        },
-      },
-      {
-        test: {
-          name: 'integration',
-          root: './sdk',
-          include: ['src/**/*.integration.test.ts'],
-          testTimeout: 120_000,
-        },
-      },
-    ],
-  },
-});