feat(cogs/problems): get random problem from NeetCode problem lists

[Kevin-Roman]

Description

Add an option to select a random question from a specific problem list. For the scope of this PR, this includes only problem sets from NeetCode directly.

Also added to the problem embed footer which problem lists the problem is part of.

Space for generalisation has been made in the code to allow future implementation of LeetCode problem sets.

[Copilot]

Pull Request Overview

This PR integrates NeetCode-based problem lists into the bot, extends the solution model to track a 250-problem list, and updates commands and embeds so users can request random questions from these new lists.

• Extend NeetcodeSolution and parsing to include neetcode250 and build problem_lists in the bot
• Update random_question_embed and question_embed to accept a ProblemList parameter and display list membership
• Introduce ProblemList enum, configure slash command options, and initialize bot.problem_lists

Reviewed Changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/utils/neetcode.py	Add neetcode250, store and populate bot.problem_lists
src/ui/embeds/problems.py	Accept problem_list in random/question embeds and show membership
src/constants.py	Define ProblemList enum, NeetCodeBasedProblemList, and titles
src/cogs/problems.py	Add ProblemListField slash-command option and pass to embeds
src/bot.py	Initialize self.problem_lists in DiscordBot

Comments suppressed due to low confidence (2)

src/constants.py:209

• The constant is named GRIND_75_QUESTION_TITLES but the list is referenced as blind_75. Rename to BLIND_75_QUESTION_TITLES (or similar) for consistency, or remove if unused.

GRIND_75_QUESTION_TITLES = {

src/utils/neetcode.py:44

• [nitpick] Using double underscores triggers name mangling and can hinder subclassing or introspection. Consider using a single underscore prefix for private methods instead.

    async def __fetch_neetcode_solutions(self) -> dict[str, NeetcodeSolution]: