Add id attr to flag components

[Flo0807]

closes #172

[Copilot]

Pull Request Overview

This PR adds an id attribute to flag components to address SVG ID conflicts when multiple flags are rendered on the same page. The implementation automatically suffixes internal SVG IDs with the provided ID or a generated unique ID to ensure uniqueness.

• Adds a templatize_ids/1 function to dynamically modify SVG IDs and their references
• Updates the component template to accept an optional id attribute with automatic unique ID generation
• Updates tests and documentation to reflect the new ID functionality

Reviewed Changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/helpers_test.exs	Comprehensive test coverage for the new templatize_ids/1 function
test/flagpack_test.exs	Updated existing tests to include ID attributes in component assertions
lib/mix/tasks/build.ex	Modified build task to process SVG files with ID templatization
lib/helpers.ex	Added templatize_ids/1 function to handle SVG ID conflicts
assets/flagpack.eex	Updated component template to support ID attribute with auto-generation

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