feat(opencode): add oh-my-opencode plugin for enhanced agent capabilities

Adds curated agents (Oracle, Librarian, Explore, Frontend Engineer),
LSP/AST tools, background agents, Claude Code compatibility layer,
and built-in MCPs (context7, exa, grep.app)

.config/opencode/opencode.json

@@ -5,6 +5,9 @@
     "disabled_providers": [
         "openai"
     ],
+    "plugin": [
+        "oh-my-opencode"
+    ],
     "instructions": [
         "docs/guidelines.md",
         "docs/development-standards.md",