Add dacshund to favorite animals

[siyabhatkal2010]

Purpose

Add one favorite-animal entry while preserving the existing list.

Verification

• I inspected git status --short.
• I inspected git diff before staging.
• I staged only the intended file.
• I inspected git diff --staged before committing.
• The pull request head is my fork's dev branch.
• The pull request base is sbruce23/PRdemo:main.
• No credential, private data, grade, or unrelated file is included.

Review question

AI-use disclosure

[siyabhatkal2010]

done.