feat(github): expose expanded review context tool params

[chubes4]

Summary

Follow up on #92 after #91 landed by exposing the optional expanded PR review context parameters through the read-only review-context ability and tool.

Changes

• Adds include_file_contents, include_base_contents, context_paths, max_file_content_chars, max_context_files, and max_total_context_chars to the datamachine/get-github-pull-review-context ability schema.
• Adds the same optional params to the get_github_pull_review_context AI tool definition.
• Extends the read-only GitHub smoke to prove the params are exposed in both ability and tool surfaces and pass through to the registered ability call.
• Includes narrow style fixes in the merged PR feat(github): expand PR review context #91 expansion helper so changed-since lint remains clean for the touched file.

Tests

• php -l inc/Abilities/GitHubAbilities.php && php -l inc/Tools/GitHubTools.php && php -l tests/smoke-github-readonly-tools.php
• php tests/smoke-github-readonly-tools.php
• homeboy lint data-machine-code --path /Users/chubes/Developer/data-machine-code@feat-readonly-github-tools --changed-since origin/main

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Updating the read-only GitHub ability/tool schemas for PR feat(github): expand PR review context #91's expanded context parameters, adjusting smoke coverage, and running verification commands. Chris remains responsible for review and merge.