Feat/confluence/get page diff tool

[iiiokojiadbi]

Description

Adds support for retrieving and comparing specific versions of Confluence pages via a new MCP tool.

Fixes: N/A

Changes

• Added get_page_version_content to PagesMixin to fetch a specific historical version of a Confluence page.
• Introduced a new MCP tool get_page_diff in servers/confluence.py to compute diffs between two page versions (by diff_url or by page_id + versions).
• Implemented diff output in two formats (unified and structured lines) and aligned error handling with existing Confluence tools.
• Added automated tests covering both new features.

Testing

• Unit tests added/updated
• Integration tests passed
• Manual checks performed: verified get_page_diff against real Confluence pages using both a full diff_url and explicit page_id + version numbers; confirmed JSON output and error handling.

Checklist

• Code follows project style guidelines (linting passes).
• Tests added/updated for changes.
• All tests pass locally.
• Documentation updated (if needed).

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity for 14 days. It will be closed if no further activity occurs. Please leave a comment or remove the 'stale' label if you believe this PR is still relevant. Thank you for your contributions!

[nimrodmoshe05-glitch]

@iiiokojiadbi SharkyND/mcp-atlassian#33
This fork is actively maintained. @SharkyND asked for you to copy this PR there also so he can merge :)