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

src/features/opencode-skill-loader/git-master-template-injection.ts

@@ -19,7 +19,7 @@ export function injectGitMasterConfig(template: string, config?: GitMasterConfig
 		const footerText =
 			typeof commitFooter === "string"
 				? commitFooter
-				: "Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)"
+				: "Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)"
 		sections.push("1. **Footer in commit body:**")
 		sections.push("```")
 		sections.push(footerText)
@@ -39,7 +39,7 @@ export function injectGitMasterConfig(template: string, config?: GitMasterConfig
 		const footerText =
 			typeof commitFooter === "string"
 				? commitFooter
-				: "Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)"
+				: "Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)"
 		sections.push("**Example (both enabled):**")
 		sections.push("```bash")
 		sections.push(
@@ -50,7 +50,7 @@ export function injectGitMasterConfig(template: string, config?: GitMasterConfig
 		const footerText =
 			typeof commitFooter === "string"
 				? commitFooter
-				: "Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)"
+				: "Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)"
 		sections.push("**Example:**")
 		sections.push("```bash")
 		sections.push(`git commit -m "{Commit Message}" -m "${footerText}"`)