feat(notes): accept a problem name as well as a problem ID

[acid-boi]

Summary

leetcode note now accepts a problem name (title slug) in addition to a numeric problem ID, so leetcode note two-sum edit works the same way leetcode note 1 edit always has.

• A name is resolved through the LeetCode API and the returned frontend ID names the note file, so both forms read and write the same file on disk.
• The resolved problem is handed to the note template generator, so creating a note by name costs a single API call rather than two.
• Input that is neither an ID nor a slug is rejected locally with a clear message, without an API round trip.
• An unknown name reports Problem "..." not found instead of dumping the raw Zod validation error, while genuine network failures still surface their message.

Motivation / Context

pick, show, hint, reset, submissions and timer all accept either a problem ID or a title slug. note was the odd one out and rejected anything non-numeric, which meant switching mental models mid-session: pick a problem by name, then look up its number to write a note about it.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• CI / Tooling / Refactoring

Checklist

• My code follows the code style of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the relevant documentation / release notes
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally (npm test)
• Type check passes (npm run typecheck)
• Linter passes (npm run lint)

How to test

npm run build

leetcode note two-sum view      # resolves to problem 1
leetcode note 1 view            # same note file, unchanged behaviour
leetcode note "Two Sum" view    # rejected locally, no API call
leetcode note not-a-problem view # clean "not found" message

Notes for the reviewer

isTitleSlug is deliberately the only new validation helper, and only note uses it for now. A follow-up PR can share one resolver across every command that takes an ID or a slug, which would also stop show and hint from printing raw Zod errors for an unknown slug.

Existing behaviour is untouched: the TUI passes a numeric ID, so its note path is unchanged, and all 354 existing tests still pass alongside the 5 new ones.

[night-slayer18]

hey @acid-boi, nice one! slug resolver is looking clean. good catch on reusing the fetched problem for the template too, saves the extra API call. error messages are way cleaner now and the tests cover the important stuff. merged 👍

[night-slayer18]

also saw your note about the shared resolver — yeah that's worth doing. if you're up for it, raise a PR that pulls that ID-or-slug resolution logic into a shared utility and wires up show, hint, reset, submissions and timer to use it. the raw Zod error thing on unknown slugs has been bugging me for a while so would be great to fix that across the board at the same time 👍