release: 2.0.0 — the agent harness operating system

Graduate 2.0.0-rc.1 to stable. Bump version across package, plugin,
marketplace, OpenCode, agent metadata, VERSION, and all localized docs.
Add 2.0.0 release notes + README sections (en/zh/pt-BR/tr), CHANGELOG
entry, and the ECC community Discord bot (dependency-free gateway client
+ guild command registrar). Update copilot-support and release-surface
tests for the sponsored-review migration and the 2.0.0 surface.

.opencode/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "ecc-universal",
-  "version": "2.0.0-rc.1",
+  "version": "2.0.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "ecc-universal",
-      "version": "2.0.0-rc.1",
+      "version": "2.0.0",
       "license": "MIT",
       "devDependencies": {
         "@opencode-ai/plugin": "^1.4.3",