docs: add Cursor integration documentation

[Saisanthosh645]

Purpose / Description

Added documentation for Cursor IDE integration, including supported features, installation instructions, configuration paths, hook event mappings, MCP server support, rules support, and known limitations.

Fixes

Fixes #1360

Approach

Created a new Cursor integration documentation page using information from the Cursor IDE registry and integration configuration files.

How Has This Been Tested?

• Verified markdown formatting.
• Checked configuration paths against the IDE registry.
• Verified hook event mappings from the Cursor registry entry.
• Reviewed documentation for completeness and consistency.

Learning

Learned how Observal manages IDE integrations, configuration scopes, MCP servers, and hook event mappings.

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