docs: promote Unreleased to v0.11.1 in CHANGELOG.md

[github-actions]

Automated by the Release workflow after cutting v0.11.1.

Moves the ## Unreleased section under a ## v0.11.1 heading.
The tag and GitHub Release already exist; this only records them in
the changelog, so merging is safe whenever convenient.

[coderabbitai]

Important

Review skipped

Bot user detected.

To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 38f8c20e-ad53-491b-81a3-961099375b78

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}