Title: Add accessibility improvements to the TUI (screen-reader-friendly output mode)

[Mkalbani]

Description

The current TUI relies on colored boxes and spatial layout that don't translate well to screen readers or low-vision users. Add a --plain or --a11y mode that renders puzzle state as clearly ordered, linear text output.

Acceptance Criteria

• --a11y CLI flag switches rendering to a linear, non-graphical text layout
• All puzzle state (board, remaining attempts, hints used, score) is fully expressible in the linear mode with no information loss compared to the graphical TUI
• Color is never the sole carrier of information in either mode (verified manually and noted in PR)
• Mode documented in README.md with a sample output snippet
• Existing TUI tests unaffected; new tests added for --a11y output format

[JesseJohn7]

Hello, I’ve gone through the requirements and I’m confident I can implement a proper solution that matches the acceptance criteria. Kindly assign this issue to me.

[grantfox-oss]

🦊 GrantFox — @JesseJohn7 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #35)
2. Your PR will be reviewed by the ThinknetCollective maintainers

Good luck! Track your progress on GrantFox.