audit: "Valid Parentheses" (#20) to Public Release

[Rowrow620]

First Timers Only

This issue is reserved for developers who are new to AlgoBuddy or open-source contributing. We know that submitting a first pull request can feel intimidating. The goal of this issue is to guide you step-by-step through making your first contribution to the AlgoBuddy repository.

Description of the Issue

The visualizer for Valid Parentheses (LeetCode #20) is currently in Developer Mode ([EXP]). We need to audit its step generator, verify active line highlighting, add an automated unit test, and promote it to Public Release status (AuditStatus::Audited).

Implementation Steps

1. Launch AlgoBuddy in Developer Mode: cargo run -- --dev
2. Select Valid Parentheses (audit: "3Sum" (#15) to Public Release #20) and scrub through the timeline steps to verify:
   • Variable snapshots and LIFO stack visualizations are accurate.
   • Source code line highlighting (code_line) matches the active execution step.
3. Open src/app.rs under #[cfg(test)] mod tests and add a unit test asserting step output for valid string "()[]{}" and invalid string "(]".
4. Open src/model/problem.rs and update audit_status(&self) to include Problem::ValidParentheses:

   match self {
       Problem::ContainsDuplicate | Problem::TwoSum | Problem::ValidAnagram | Problem::ValidParentheses => {
           AuditStatus::Audited
       }
       _ => AuditStatus::Unaudited,
   }

Acceptance Criteria

To merge a pull request for this issue:

• Code Formatting: cargo fmt --all -- --check completes without warnings.
• All Tests Pass: cargo test passes 100% of unit tests.
• Issue Solved: Valid Parentheses visualizer appears in Public Release Mode without requiring --dev.
• Clean Git Branch: Changes are committed to a feature branch targeting dev.

Step-by-Step Contribution Guide

• Claim this issue: Comment below that you are working on this issue to receive assignment.
• Fork and Branch: Create a new branch off dev named audit-valid-parentheses.
• Make and Test Changes: Run cargo fmt --all and cargo test locally to verify build health.
• Submit PR: Push your branch to GitHub and create a Pull Request targeting the dev branch.

Additional Information

• Contributing Guide
• README