This PR adds a simplified Linear toolkit focused on core functionality:
## What's Included
**Tools:**
- `get_issue` - Get detailed information about Linear issues
- `get_teams` - Get team information and details
**Models:**
- `DateRange` enum with comprehensive date range support (TODAY,
YESTERDAY, THIS_WEEK, LAST_WEEK, THIS_MONTH, LAST_MONTH, THIS_YEAR,
LAST_YEAR, LAST_7_DAYS, LAST_30_DAYS)
- Timezone-aware datetime handling following Google toolkit patterns
## What's Simplified
This toolkit has been streamlined by removing:
- Cycles management tools
- Projects management tools
- Users management tools
- Workflows management tools
- Corresponding tests and evaluations for removed features
## Quality Assurance
- All linting and formatting checks pass
- Comprehensive test coverage for included functionality
- Follows established patterns from Google toolkit
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Co-authored-by: Eric Gustin <34000337+EricGustin@users.noreply.github.com>