feat(parser): add xml:lang tracking and license field support

[bug-ops]

Summary

Phase 2 of API parity implementation. Adds xml:lang tracking to RSS parser and license field extraction for both RSS and Atom formats.

Changes

Core Library

• Add extract_xml_lang() helper function in common.rs
• RSS parser: Track xml:lang at channel and item levels with inheritance
• RSS parser: Extract license from <creativeCommons:license> and <license> tags
• Atom parser: Extract license from <link rel="license"> elements
• Add license: Option<String> field to FeedMeta and Entry structs

Python Bindings

• Add license getter to FeedMeta and Entry classes
• xml:lang accessible via title_detail.language, summary_detail.language, etc.

Node.js Bindings

• Add license field to FeedMeta and Entry structs
• Update TypeScript definitions with license?: string

Test Plan

• 481 tests pass
• RSS xml:lang tests (channel, item, inheritance, empty attribute)
• RSS license tests (creativeCommons namespace, plain tag)
• Atom license tests (link rel="license")
• cargo clippy --all-targets clean
• cargo make ci-lint-stable passes

Reviews Completed

Review	Status	Key Findings
Performance	✅ APPROVED	+0.4% overhead, optimal implementation
Security	✅ APPROVED	DoS protection via max_attr_length
Testing	✅ APPROVED	TypeScript definitions fixed
Code Review	✅ APPROVED	Ready for merge

API Compatibility

Matches Python feedparser behavior:

• feed.title_detail.language returns xml:lang value
• feed.license returns license URL
• entry.summary_detail.language returns xml:lang value
• entry.license returns license URL

No breaking changes.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.15668% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/feedparser-rs-core/src/parser/rss.rs	97.59%	4 Missing ⚠️

@@            Coverage Diff             @@
##             main      #27      +/-   ##
==========================================
+ Coverage   90.85%   91.08%   +0.22%     
==========================================
  Files          32       32              
  Lines        6245     6447     +202     
==========================================
+ Hits         5674     5872     +198     
- Misses        571      575       +4     

Flag	Coverage Δ
rust-core	91.08% <98.15%> (+0.22%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
crates/feedparser-rs-core/src/parser/atom.rs	89.71% <100.00%> (+0.54%)	⬆️
crates/feedparser-rs-core/src/parser/common.rs	77.02% <100.00%> (+1.66%)	⬆️
crates/feedparser-rs-core/src/types/entry.rs	87.69% <ø> (ø)
crates/feedparser-rs-core/src/types/feed.rs	96.36% <ø> (ø)
crates/feedparser-rs-core/src/parser/rss.rs	94.73% <97.59%> (+0.30%)	⬆️

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[Copilot]

Pull request overview

This PR implements Phase 2 of API parity with Python feedparser by adding xml:lang attribute tracking to RSS feeds and license field extraction for both RSS and Atom formats. The implementation adds a new extract_xml_lang() helper function in the common parser utilities and extends both RSS and Atom parsers to extract license information from various tag formats. These changes enhance compatibility with Python feedparser's behavior while maintaining the project's performance and security standards.

Key Changes:

• Added xml:lang tracking with inheritance (channel-level → item-level) in RSS parser, storing language info in TextConstruct objects
• Added license field extraction from <creativeCommons:license>, <license> (RSS), and <link rel="license"> (Atom)
• Extended Python and Node.js bindings to expose the new license field

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/feedparser-rs-core/src/types/feed.rs	Added license: Option<String> field to FeedMeta struct
crates/feedparser-rs-core/src/types/entry.rs	Added license: Option<String> field to Entry struct
crates/feedparser-rs-core/src/parser/common.rs	Added extract_xml_lang() helper with DoS protection via max_attribute_length
crates/feedparser-rs-core/src/parser/rss.rs	Implemented xml:lang tracking with inheritance and license extraction for RSS; added 144 lines of comprehensive tests
crates/feedparser-rs-core/src/parser/atom.rs	Added license extraction from <link rel="license"> elements; added 44 lines of tests
crates/feedparser-rs-py/src/types/feed_meta.rs	Added license getter for Python FeedMeta class
crates/feedparser-rs-py/src/types/entry.rs	Added license getter for Python Entry class
crates/feedparser-rs-node/src/lib.rs	Added license field to Node.js FeedMeta and Entry structs with type conversions
crates/feedparser-rs-node/index.d.ts	Added TypeScript definitions for license?: string fields