Improve contrast for completed poll results

[Dimillian]

Motivation

• Poll option text can be hard to read when a custom tintColor is used because the completed-result fill was fully opaque with the same tint.
• The uncompleted poll background uses opacity(0.4), so increasing the completed result opacity improves legibility.
• The change aims to make poll results more readable across different user-selected themes.

Description

• Updated Packages/StatusKit/Sources/StatusKit/Poll/StatusPollView.swift to use theme.tintColor.opacity(0.6) for the result fill.
• The change targets the RoundedRectangle used inside the _PercentWidthLayout that renders the option result width.
• This is a single-line visual tweak and does not alter layout or interaction logic.

Testing

• No automated tests were run for this change.
• A local commit and PR were created to capture the change for review.

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Codex Task