feat(cli): support paths/URIs for --agent

[RomneyDa]

Description

support e.g. cn --agent this-agent.md or cn --agent file://path/to/agent.md

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Summary by cubic

Add CLI support for loading agent files from local paths and file:// URIs with --agent, alongside existing hub slugs. This lets you run local agent definitions like: cn --agent ./agent.md.

• New Features
  • Accepts --agent values like ./agent.md and file:///abs/path/agent.md.
  • If the value looks like owner/package, tries the hub first, then falls back to a path.
  • Improves error messages with the original input and root cause.

^{Written for commit 1e96371. Summary will update automatically on new commits.}

[github-actions]

⚠️ PR Title Format

Your PR title doesn't follow the conventional commit format, but this won't block your PR from being merged. We recommend using this format for better project organization.

Expected Format:

<type>[optional scope]: <description>

Examples:

• feat: add changelog generation support
• fix: resolve login redirect issue
• docs: update README with new instructions
• chore: update dependencies

Valid Types:

feat, fix, docs, style, refactor, perf, test, build, ci, chore, revert

This helps with:

• 📝 Automatic changelog generation
• 🚀 Automated semantic versioning
• 📊 Better project history tracking

This is a non-blocking warning - your PR can still be merged without fixing this.

[github-actions]

✅ Review Complete

Code Review Summary

⚠️ Continue configuration error. Please verify that the assistant exists in Continue Hub.

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[cubic-dev-ai]

No issues found across 1 file