fix: content drive clean-up - animation, loading states, and type fixes

[zJaaal]

Summary

• Replace Angular @slideAnimation trigger with CSS-based animate.enter/animate.leave attributes to remove the deprecated @angular/animations dependency from the toolbar component
• Change toolbar tree-toggler visibility from conditional rendering (@if) to CSS-based show/hide (opacity/visibility/width) so the toggle button animates smoothly instead of popping in/out
• Fix folder list view loading skeleton: extract loadingRow into a reusable <ng-template> and show it inside emptymessage during loading so rows appear correctly on initial load and page changes
• Update $loadingRows signal to track the current page size and emit correctly sized skeleton row arrays on pagination
• Fix optional chaining on $dialog signal calls in the shell component to prevent null-access errors
• Fix $folder input type from null default to undefined (aligns with Angular signal input best practices)
• Fix typing errors and update tests to match new DOM structure (toggler now always rendered, assertions check styles rather than element presence)

Screen.Recording.2026-02-26.at.12.05.11.PM.mov

Test plan

• Navigate to Content Drive portlet and verify the folder list renders skeleton loading rows on initial load
• Verify that changing pages shows the correct number of skeleton rows matching the page size
• Expand/collapse the folder tree panel and verify the tree-toggler button animates smoothly (fades rather than snapping in/out)
• Click "Add New" and verify the toolbar button animates in/out when switching between normal and multi-selection mode
• Open a dialog (e.g., create folder), verify it opens and closes correctly without null-reference errors
• Run unit tests: yarn nx test dot-content-drive-portlet and confirm all pass
• Run unit tests for the UI lib: yarn nx test dot-content-drive-ui and confirm all pass

🤖 Generated with Claude Code

This PR fixes: #34108

[semgrep-code-dotcms-test]

Legal Risk

The following dependencies were released under a license that
has been flagged by your organization for consideration.

Recommendation

While merging is not directly blocked, it's best to pause and consider what it means to use this license before continuing. If you are unsure, reach out to your security team or Semgrep admin to address this issue.

MPL-2.0

• axe-core 4.11.1
• lightningcss-android-arm64 1.30.2
• lightningcss-darwin-arm64 1.30.2
• lightningcss-darwin-x64 1.30.2
• lightningcss-freebsd-x64 1.30.2
• lightningcss-linux-arm-gnueabihf 1.30.2
• lightningcss-linux-arm64-gnu 1.30.2
• lightningcss-linux-arm64-musl 1.30.2
• lightningcss-linux-x64-gnu 1.30.2
• lightningcss-linux-x64-musl 1.30.2
• lightningcss-win32-arm64-msvc 1.30.2
• lightningcss-win32-x64-msvc 1.30.2
• lightningcss 1.30.2

[semgrep-code-dotcms-test]

Legal Risk

The following dependencies were released under a license that
has been flagged by your organization for consideration.

Recommendation

While merging is not directly blocked, it's best to pause and consider what it means to use this license before continuing. If you are unsure, reach out to your security team or Semgrep admin to address this issue.

MPL-2.0

• axe-core 4.11.1
• lightningcss-android-arm64 1.30.2
• lightningcss-darwin-arm64 1.30.2
• lightningcss-darwin-x64 1.30.2
• lightningcss-freebsd-x64 1.30.2
• lightningcss-linux-arm-gnueabihf 1.30.2
• lightningcss-linux-arm64-gnu 1.30.2
• lightningcss-linux-arm64-musl 1.30.2
• lightningcss-linux-x64-gnu 1.30.2
• lightningcss-linux-x64-musl 1.30.2
• lightningcss-win32-arm64-msvc 1.30.2
• lightningcss-win32-x64-msvc 1.30.2
• lightningcss 1.30.2