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.

.claude-plugin/marketplace.json

@@ -12,7 +12,7 @@
       "name": "ecc",
       "source": "./",
       "description": "Harness-native ECC operator layer - 64 agents, 261 skills, 84 legacy command shims, reusable hooks, rules, selective install profiles, and production-ready workflows for Claude Code, Codex, OpenCode, Cursor, and related agent harnesses",
-      "version": "2.0.0-rc.1",
+      "version": "2.0.0",
       "author": {
         "name": "Affaan Mustafa",
         "email": "me@affaanmustafa.com"

.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "ecc",
-  "version": "2.0.0-rc.1",
+  "version": "2.0.0",
   "description": "Harness-native ECC plugin for engineering teams - 64 agents, 261 skills, 84 legacy command shims, reusable hooks, rules, MCP conventions, and operator workflows for Claude Code plus adjacent agent harnesses",
   "author": {
     "name": "Affaan Mustafa",