[AaronDDM]

Prepares Ruby SDK 6.9.0 with the pending HTTP 207 Multi-Status fix, contact webhook constants, and documentation for contact metadata and custom tracking domains. Finalizes the dated changelog and version, fixes gem metadata and reference links, and includes the README, changelog, and license in the gem.

Requires HTTParty >= 0.24.0 to exclude CVE-2025-68696 and YARD >= 0.9.44 for known documentation server path traversal fixes. Updates the coverage formatter for current REXML compatibility and declares a YARD-compatible RDoc development dependency so documentation also builds on Ruby 4.0.

Release checks now use explicit Ruby 3.0/3.1/3.2 version strings, preserving the existing protected branch check names. CI builds the gem on each version and verifies that reference documentation actually produced HTML. The local test command now matches the Ruby 3.0+ suite.

Validation on Ruby 4.0.7 with freshly resolved dependencies:

• bin/test: 320 examples, 0 failures; 97.96% line coverage; coverage XML parses successfully.
• bundle exec rubocop --config .rubocop.yml: 80 files, no offenses.
• bundle exec yard and generated HTML check: passed without documentation warnings.
• gem build nylas.gemspec and gem manifest verification: passed.
• Fresh isolated gem install: SDK load, client initialization, HTTP 207 support, and contact webhook constants passed.
• bundle-audit check --update: no vulnerabilities found after dependency updates.

Publication follows successful release PR checks and merge.

[qasim-nylas]

LGTM 👍