feat(weather): add weather search adapter

[vkop007]

Description

This PR introduces the new Weather adapter to OpenCLI. It leverages the completely free, lightning-fast wttr.in JSON API to stream real-time global weather telemetry directly into the terminal without requiring browser sessions or API keys.

Commands Added (opencli weather):

• search - Instantly fetch live environmental conditions for any city or location (e.g., opencli weather search --location "San Francisco").

Note: Fully documented and structurally integrated into the VitePress website and project READMEs.

Related issue: N/A

Type of Change

• 🐛 Bug fix
• ✨ New feature
• 🌐 New site adapter
• 📝 Documentation
• ♻️ Refactor
• 🔧 CI / build / tooling

Checklist

• I ran the checks relevant to this PR (opencli validate)
• I updated tests or docs if needed (README.md and VitePress configs)
• I included output or screenshots when useful

Documentation (if adding/modifying an adapter)

• Added doc page under docs/adapters/ (docs/adapters/browser/weather.md)
• Updated docs/adapters/index.md table
• Updated sidebar in docs/.vitepress/config.mts

Screenshots / Output

$ opencli weather search --location "San Francisco"

  weather/search
┌───────────┬──────┬───────┬──────────┬────────┐
│ Condition │ Temp │ Feels │ Humidity │ Wind   │
├───────────┼──────┼───────┼──────────┼────────┤
│ Clear     │ 13°C │ 13°C  │ 80%      │ 5 km/h │
└───────────┴──────┴───────┴──────────┴────────┘
1 items · 1.9s · weather/search