feat(ng-dev/pr): surface caretaker note comment inline during merge

[mattrbeck]

When merging a PR that has the merge: caretaker note label applied, the CLI previously only showed a warning and a quick link to the PR on GitHub.

This change:

1. Surfaces the matching caretaker note comment body directly inline in the CLI confirmation prompt so caretakers do not have to leave the terminal to read it on GitHub.
2. Applies 16-color ANSI magenta formatting to the quoted comment block to make the caretaker note clearly distinguishable in the terminal.
3. Preserves existing fallback behavior with the PR link if no single matching caretaker note comment is found (e.g. 0 or multiple matching comments).

[gemini-code-assist]

Code Review

This pull request introduces functionality to fetch and display caretaker notes directly from GitHub pull request comments when prompting the caretaker during a merge. It adds helper functions to extract, match (via regex), and format these notes, along with corresponding unit tests. The review feedback highlights a security concern where caretaker notes could be spoofed by untrusted GitHub users. It suggests restricting the notes to comments authored by trusted users (e.g., owners, members, or collaborators) and adding unit tests to verify this behavior.