docs: update all GitHub URLs from oh-my-opencode to oh-my-openagent

The GitHub repository was renamed from oh-my-opencode to oh-my-openagent,
but all documentation, scripts, and source code references still pointed
to the old repository name. This caused confusion for users who saw
'oh-my-opencode' in docs but a different repo name on GitHub.

Updated all references across:
- README files (en, ko, ja, zh-cn, ru)
- CONTRIBUTING.md
- docs/ (installation, overview, configuration, etc.)
- Source code (schema URLs, GitHub API calls, issue links)
- Test snapshots

The npm package name remains 'oh-my-opencode' (unchanged).

Fixes: https://x.com/Dhruv14588676/status/2031216617762468348

docs/troubleshooting/ollama.md

@@ -67,7 +67,7 @@ The proper fix requires Claude Code SDK to:
 3. Merge `tool_calls` from multiple lines
 4. Return a single merged response
 
-**Tracking**: https://github.com/code-yeongyu/oh-my-opencode/issues/1124
+**Tracking**: https://github.com/code-yeongyu/oh-my-openagent/issues/1124
 
 ## Workaround Implementation
 
@@ -114,7 +114,7 @@ curl -s http://localhost:11434/api/chat \
 
 ## Related Issues
 
-- **oh-my-opencode**: https://github.com/code-yeongyu/oh-my-opencode/issues/1124
+- **oh-my-opencode**: https://github.com/code-yeongyu/oh-my-openagent/issues/1124
 - **Ollama API Docs**: https://github.com/ollama/ollama/blob/main/docs/api.md
 
 ## Getting Help