🔊 feat!: make the three silent failures loud

Every change here answers one question: where does cereale currently fail
without saying so?

**Vite 8 / Vitest 4 drop decorators silently.** Both transform with oxc,
which does not implement the standard decorator transform and does not
report that. `vitest` prints "0 test" beside a bare SyntaxError, and
`vite build` reports success while emitting a bundle that throws on first
import. Ship the plugin that fixes it as `cereale/vite`, transforming with
esbuild and falling back to tsc — cereale depends on neither. The library's
own suite now runs through it, so it is exercised by every test.

**Legacy decorators died opaquely.** With `experimentalDecorators: true`,
still the default in most existing TypeScript projects, decorators are
invoked as (prototype, "name") and cereale raised "TypeError: Cannot convert
undefined or null to object". All decorators now resolve metadata through
one checkpoint that names the tsconfig setting instead, and reject
application to a method, getter or accessor field.

**Values JSON cannot carry were emptied.** A populated Map serialized to
{}, a Uint8Array to index-keyed noise, a bigint straight through so the
caller's own JSON.stringify threw somewhere unrelated. All now raise
JsonMappingError naming the property path and both ways out. Covers what a
@JsonSerialize serializer returns, sync or async. Circular-reference and
depth errors name the path too.

Also fixed: defineRule on a subclass with no decorators of its own wrote
the rule into its base class, because the base's metadata object is
inherited through the static prototype chain and `??=` found it non-nullish.

The README's toolchain table (tsc, esbuild, swc ✅, oxc ❌) is now executed
by a test rather than asserted, and the positioning leads with
class-validator + class-transformer, the stack cereale actually replaces,
rather than Zod, which it deliberately is not.

193 -> 249 tests.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SAcqrz3FcadkYr3xG32CjK

package.json

@@ -1,7 +1,7 @@
 {
   "name": "cereale",
-  "version": "0.2.0",
-  "description": "Strongly typed JSON mapping and validation for TypeScript classes — validated domain objects, not validated data",
+  "version": "0.3.0",
+  "description": "Strongly typed JSON mapping and validation for TypeScript classes — validated domain objects, not validated data. A zero-dependency replacement for class-validator + class-transformer, on TC39 standard decorators.",
   "type": "module",
   "main": "./dist/cjs/index.js",
   "module": "./dist/esm/index.js",
@@ -11,6 +11,11 @@
       "types": "./dist/esm/index.d.ts",
       "import": "./dist/esm/index.js",
       "require": "./dist/cjs/index.js"
+    },
+    "./vite": {
+      "types": "./dist/esm/vite.d.ts",
+      "import": "./dist/esm/vite.js",
+      "require": "./dist/cjs/vite.js"
     }
   },
   "sideEffects": [
@@ -44,11 +49,13 @@
     "json",
     "validation",
     "decorators",
+    "standard-decorators",
     "typescript",
-    "zod-alternative",
     "dto",
     "serialization",
-    "class-validator"
+    "class-validator",
+    "class-transformer",
+    "class-validator-alternative"
   ],
   "author": "Avalon Vanguard",
   "license": "MIT",
@@ -58,6 +65,7 @@
   "homepage": "https://github.com/Avalon-Vanguard/cereale#readme",
   "devDependencies": {
     "@eslint/js": "^10.0.1",
+    "@swc/core": "^1.15.47",
     "@types/node": "^25.6.0",
     "@vitest/coverage-v8": "^4.1.4",
     "esbuild": "^0.25.0",