feat(github): add GitHub adapter with 5 public API commands

[kagura-agent]

What

Adds a native GitHub adapter with 5 commands using GitHub's public REST API. No authentication required, no browser needed.

Commands

Command	Description	Example
github trending	Trending repos (recent stars)	opencli github trending --language python --limit 5
github search	Search repositories	opencli github search --query "agent memory" --limit 10
github repo	Repository details	opencli github repo --owner jackwener --name opencli
github user	User profile	opencli github user --username jackwener
github issues	List repository issues	opencli github issues --owner jackwener --name opencli --state open

Why

GitHub is the most used developer platform and a natural fit for an AI-agent CLI tool. Surprisingly it wasn't covered yet. All commands are pure YAML declarative adapters — zero TypeScript, minimal maintenance.

Implementation

• 5 YAML files in src/clis/github/
• Uses GitHub REST API v3 (api.github.com)
• strategy: public, browser: false
• Trending uses GitHub search API (sorted by stars, filtered by creation date) since the unofficial trending APIs are unreliable

Testing

All 5 commands manually verified:

$ opencli github search --query openclaw --limit 3
┌──────┬───────────────────────────────────┬────────┬───────┬────────────┬───────────────────────┐
│ Rank │ Name                              │ Stars  │ Forks │ Language   │ Description           │
├──────┼───────────────────────────────────┼────────┼───────┼────────────┼───────────────────────┤
│ 1    │ openclaw/openclaw                 │ 340056 │ 67032 │ TypeScript │ Your own personal AI… │
└──────┴───────────────────────────────────┴────────┴───────┴────────────┴───────────────────────┘

$ opencli github trending --limit 3
┌──────┬───────────────────────┬───────┬───────┬────────────┬─────────────────────────┐
│ Rank │ Name                  │ Stars │ Forks │ Language   │ Description             │
├──────┼───────────────────────┼───────┼───────┼────────────┼─────────────────────────┤
│ 1    │ slavingia/skills      │ 5199  │ 368   │ -          │ Claude Code skills…     │
│ 2    │ larksuite/cli         │ 2622  │ 116   │ Go         │ A command-line tool…    │
│ 3    │ magnum6actual/flipoff │ 2308  │ 280   │ JavaScript │ Free split-flap…        │
└──────┴───────────────────────┴───────┴───────┴────────────┴─────────────────────────┘