test(translator): add data-driven coverage, bug-exposing cases, and real provider smoke

- matrix.js generates N providers x M models from PROVIDER_MODELS
- coverage-all-models + format-roundtrip for structural/semantic checks
- bugs-* files expose known translation issues via it.fails
- real/smoke-providers runs full handleChatCore path against live providers (RUN_REAL=1), concurrent
- registerAll.js eagerly imports translators (Vitest ESM require fix)
- vitest.config: array aliases for subpaths + maxConcurrency 60

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/vitest.config.js

@@ -9,15 +9,17 @@ export default defineConfig({
     environment: "node",
     globals: true,
     include: ["**/*.test.js"],
+    // Allow many it.concurrent cases (real provider smoke runs ~50 providers in parallel)
+    maxConcurrency: 60,
     // Suppress noisy console output from handlers under test
     silent: false,
   },
   resolve: {
-    alias: {
-      // Resolve open-sse/* imports to the actual local package
-      "open-sse": resolve(__dirname, "../open-sse"),
-      // Resolve @/* imports to src directory
-      "@": resolve(__dirname, "../src"),
-    },
+    // Use array form so subpath aliases (e.g. "@/lib/db/index.js") resolve correctly.
+    alias: [
+      { find: /^open-sse\//, replacement: resolve(__dirname, "../open-sse") + "/" },
+      { find: "open-sse", replacement: resolve(__dirname, "../open-sse") },
+      { find: /^@\//, replacement: resolve(__dirname, "../src") + "/" },
+    ],
   },
 });