fix(plugin-config): ensure both legacy and renamed config files are discovered (fixes #3133)

[MoerAI]

Summary

• make shared plugin config path discovery resolve whichever oh-my-openagent or oh-my-opencode config file actually exists
• add regression coverage for legacy-only detection and canonical-over-legacy precedence in shared config path resolution

Problem

Some code paths still treated the plugin config path as a fixed canonical oh-my-openagent.json fallback instead of resolving the active file on disk. That made discovery inconsistent when users only had a legacy oh-my-opencode.json[c] file or a .jsonc variant, even though the loader itself supports both basenames during the rename transition.

Fix

Update getOpenCodeConfigPaths() to use detectPluginConfigFile() so shared path resolution consistently returns the real active plugin config file across old/new basenames and .json/.jsonc extensions. Add regression tests to lock in legacy fallback behavior and canonical-name precedence when both variants are present.

Changes

File	Change
src/shared/opencode-config-dir.ts	Resolve omoConfig from detected plugin config files instead of a fixed canonical .json path
src/shared/opencode-config-dir.test.ts	Add regression tests for legacy-only detection and canonical precedence

Fixes #3133

---

Summary by cubic

Ensure plugin config discovery resolves the actual file on disk, whether legacy oh-my-opencode or renamed oh-my-openagent, across .json/.jsonc. Canonical is preferred when both exist. Fixes #3133.

• Bug Fixes
  • Update getOpenCodeConfigPaths() to use detectPluginConfigFile() and set omoConfig to the detected path, preferring oh-my-openagent when both variants exist.
  • Add regression tests for legacy-only detection and canonical-over-legacy precedence.

^{Written for commit dacaeb4. Summary will update on new commits.}

[MoerAI]

I have read the CLA Document and I hereby sign the CLA

[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Auto-approved: Fixes config discovery inconsistency by using existing detection utility and adds comprehensive regression tests for legacy/canonical precedence.}