sharp histogram corners

[SebastianEggli]

Description

Sharp histogram corners instead of round ones, so clipping is visible in the histogram

Type of Change

• Bug fix
• New feature
• Breaking change
• Performance improvement
• Code refactoring
• Documentation update
• UI/UX improvement
• Build/CI or Dependency update

Changes Made

Sharp histogram corners

Testing

• These changes were tested locally by a human and confirmed to work.
• I haven't added any automated tests to the code because the codebase currently lacks a test suite.

Test Configuration:

Ubuntu

Checklist

• My code follows the project's code style
• I haven't added unnecessary AI-generated code comments
• My changes generate no new warnings or errors

AI Disclaimer:

Please state the involvement of AI in this PR:

• This PR is created by an AI agent
• This PR is mostly AI-generated but edited/merged together by a human
• This PR was handwritten with AI assistance (spell check, logic suggestions, error resolving)
• This PR contains only blood, sweat, and coffee (AI-free)