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.

.codex-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "ecc",
-  "version": "2.0.0-rc.1",
+  "version": "2.0.0",
   "description": "Harness-native ECC workflows for Codex: shared skills, production-ready MCP configs, and selective-install-aligned conventions for TDD, security scanning, code review, and autonomous development.",
   "author": {
     "name": "Affaan Mustafa",