feat: introduce CHANGELOG.md mechanism and release pipeline integration (#182)

* feat: introduce CHANGELOG.md mechanism and release pipeline integration

- Create CHANGELOG.md with history from git (v2.3.10 - v2.3.14)
- Add fastlane/changelog_helper.rb for changelog extraction and validation
- Modify release.yml to validate changelog exists before release
- Update release.yml to generate GitHub Release notes from CHANGELOG.md
- Update release.yml to generate Google Play whatsnew from CHANGELOG.md
- Add validate_changelog and version_info lanes to Fastfile
- Add changelog validation to deploy_beta and deploy_production lanes

This aligns with the iOS version's changelog workflow where:
- Developers manually maintain CHANGELOG.md with version entries
- Release will fail if no changelog entry exists for current version
- Release notes are automatically extracted from CHANGELOG.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix: address Copilot review comments

- Fix awk pattern to use proper regex match for version detection
- Use -le instead of -lt for character limit comparison (include at exact limit)
- Fix comment wording: "add entry" instead of "update"
- Update CHANGELOG.md example to use realistic version format
- Add clarifying comment about RELEASE_NOTES.md vs CHANGELOG.md
- Fix regex pattern in changelog validation to handle optional build number
- Remove unnecessary .strip() call in Ruby version extraction
- Update function comment to clarify "3 versions total"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: graycreate