chore: migrate from mypy to ty type checker

[dreamiurg]

Summary

• Replace mypy with Astral's ty (10-100x faster, Rust-based)
• Update pyproject.toml, pre-commit, and CI workflow
• Fix real type errors ty detected that mypy missed

🤖 Generated with Claude Code

[coderabbitai]

Caution

Review failed

The pull request is closed.

📝 Walkthrough

Summary by CodeRabbit

• Chores

  • Refreshed type checking and dependency management configuration across continuous integration, pre-commit hooks, and project development setup.
  • Corrected test data field value for consistency.

• Tests

  • Enhanced test coverage with additional validations ensuring seasonal pattern calculations work correctly across various window configurations and year wraparound scenarios.

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Walkthrough

The PR replaces mypy with ty as the type-checking tool across CI workflows, pre-commit configuration, and project dependencies. Configuration is migrated from [tool.mypy] to [tool.ty.environment]. Test files are updated with type corrections and additional assertions.

Changes

Cohort / File(s)	Summary
Type-checker tool replacement .github/workflows/ci.yml, .pre-commit-config.yaml, CLAUDE.md, pyproject.toml	Replaces mypy with ty across CI workflows, pre-commit hooks, and dependency declarations. Migrates type-checking configuration from [tool.mypy] to [tool.ty.environment] in pyproject.toml; removes types-beautifulsoup4 dependency.
Test updates tests/test_cli_errors.py	Corrects elevation_ft from string "1000" to integer 1000 in test data.
Test assertions tests/test_statistics.py	Adds assertions verifying that seasonal_pattern is not None across three test scenarios: seasonal window variations and year wraparound.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• ci: add badges and GitHub Actions CI workflow #20: Adds initial mypy configuration and typing dependencies that this PR replaces with ty.

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📜 Recent review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 35126c0 and 97a7c63.

📒 Files selected for processing (6)

• .github/workflows/ci.yml
• .pre-commit-config.yaml
• CLAUDE.md
• pyproject.toml
• tests/test_cli_errors.py
• tests/test_statistics.py

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.21%. Comparing base (35126c0) to head (97a7c63).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #63   +/-   ##
=======================================
  Coverage   91.21%   91.21%           
=======================================
  Files           8        8           
  Lines        1081     1081           
=======================================
  Hits          986      986           
  Misses         95       95           

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