Changelog: Feature: Add detailed runtime complexity analysis for version range override resolution.
Docs: https://github.com/conan-io/docs/pull/XXXX

• Refer to the issue that supports this Pull Request.
• If the issue has missing info, explain the purpose/use case/pain/need that covers this Pull Request.
  This PR adds a detailed analysis document (version_override_complexity_analysis.md) to explain the runtime complexity of version range override resolution, specifically within the test_override method and underlying graph building logic. The document identifies the root causes (recursive downstream traversal, repeated conflict checking, hash collisions) for the observed O(N² × D) complexity and proposes optimization opportunities. This addresses the need to understand performance bottlenecks in dependency graph resolution.
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• I've followed the PEP8 style guides for Python code.
• I've opened another PR in the Conan docs repo to the develop branch, documenting this one.