Transformation filter

[irees]

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[github-actions]

Generated Code Check ✅

All generated code is up to date.

[Copilot]

Pull Request Overview

Implements a transformation filter system for GTFS data processing that allows field-level transformations on entities using various string manipulation functions. This adds capability to apply transforms like uppercase, lowercase, trim, URL escaping, and space-to-underscore replacement.

Key changes:

• New TransformFilter implementation with string transformation functions
• Comprehensive test coverage for transformation scenarios
• Integration with existing filtering infrastructure using SetterFilter patterns

Reviewed Changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
extract/transform_filter.go	Core implementation of TransformFilter with transformation functions and entity processing logic
extract/transform_filter_test.go	Comprehensive test suite covering all transformation scenarios and edge cases
extract/setterfilter.go	Enhanced error handling and wildcard entity matching support
cmds/extract_cmd.go	Added exclude-unused-routes functionality for filtering out routes without trips
copier/copier.go	Improved error message to include extension type information
doc/cli/*.md	Updated auto-generated documentation timestamps

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