feat(dictionary): add dictionary search, synonyms, and examples adapters

[vkop007]

Description

This PR introduces the powerful new Dictionary adapter to OpenCLI. It leverages the completely free, public api.dictionaryapi.dev robust JSON endpoint to bring a reliable spell checker, dictionary, and thesaurus straight into the developer terminal.

Commands Added (opencli dictionary):

• search - Get the phonetic pronunciation, part of speech, and primary definition of any word (e.g., opencli dictionary search --word "serendipity").
• synonyms - Extract up to 5 related synonyms for a given word by scrubbing the entire JSON definitions tree.
• examples - Find real-world sentence usage examples for complex vocabulary (falls back elegantly if a word lacks examples).

Implementation Note: The YAML dataset extraction mappings were custom-built using recursive ES6 IIFEs to safely traverse variable-depth JSON nodes. This guarantees 100% crash protection against unpredictable empty arrays in the Dictionary API.

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 integration and VitePress docs)
• I included output or screenshots when useful

Documentation (if adding/modifying an adapter)

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

Screenshots / Output

$ opencli dictionary search --word serendipity

  dictionary/search
┌─────────────┬─────────────────────┬──────┬──────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ Word        │ Phonetic            │ Type │ Definition                                                                                                   │
├─────────────┼─────────────────────┼──────┼──────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ serendipity │ /ˌsɛ.ɹən.ˈdɪ.pɪ.ti/ │ noun │ A combination of events which have come together by chance to make a surprisingly good or wonderful outcome. │
└─────────────┴─────────────────────┴──────┴──────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
1 items · 0.8s · dictionary/search

$ opencli dictionary synonyms --word serendipity

  dictionary/synonyms
┌─────────────┬──────────────┐
│ Word        │ Synonyms     │
├─────────────┼──────────────┤
│ serendipity │ chance, luck │
└─────────────┴──────────────┘
1 items · 0.6s · dictionary/synonyms

$ opencli dictionary examples --word perfect

  dictionary/examples
┌─────────┬──────────────────┐
│ Word    │ Example          │
├─────────┼──────────────────┤
│ perfect │ a perfect circle │
└─────────┴──────────────────┘
1 items · 0.8s · dictionary/examples