fix(about): drop stale swift-markdown-ui acknowledgement

[BlackHole1]

The app stopped depending on swift-markdown-ui once the update window began parsing release notes itself via AttributedString(markdown:), but the Acknowledgements sheet still credited it — showing users a library that ships nowhere in the build.

Remove the entry from the credits list and sync the two docs that described it: DESIGN.md's acknowledgements rundown and RELEASING.md's now-false claim that the update window renders with swift-markdown-ui (it uses its own parser).

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 01bc96c4-3568-480b-8407-3ad1ebd281d1

📥 Commits

Reviewing files that changed from the base of the PR and between f3b7191 and 442cf30.

📒 Files selected for processing (3)

• Sources/LockIME/UI/AboutView.swift
• docs/DESIGN.md
• docs/RELEASING.md

💤 Files with no reviewable changes (1)

• Sources/LockIME/UI/AboutView.swift

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Summary by CodeRabbit

• Bug Fixes
  • Updated the app’s acknowledgements list so it shows the correct set of included libraries.
  • Adjusted the About window’s license acknowledgements content to match the current dependencies.

Walkthrough

The swift-markdown-ui library is removed from the acknowledgements displayed in the About window. In AcknowledgementsView, its .init(...) entry is deleted from the libraries array. docs/DESIGN.md is updated to list PermissionFlow instead of swift-markdown-ui in the description of the acknowledgements sheet. docs/RELEASING.md is updated to state that the update window renders embedded markdown using the app's own parser rather than swift-markdown-ui.

Possibly related PRs

• oomol-lab/LockIME#21: Also modifies the About-window acknowledgements and docs/RELEASING.md in relation to removing swift-markdown-ui/MarkdownUI references for release-notes parsing.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title follows the required type(scope): subject format and accurately reflects the stale acknowledgment removal.
Description check	✅ Passed	The description is directly related to the code and docs changes, explaining the removed dependency credit and documentation updates.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch fix/drop-stale-markdown-ui-acknowledgement

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