feat(settings): add search for installed plugins

[AdityaKr015]

Summary

This PR adds an in-page search field to Plugins section that filters installed plugins by name, id, description, and source (case-insensitive). The query is debounced, resets scroll on change, clears on section navigation, and shows a "No plugins match" with the query message when nothing matches. The "Update all (N)" badge counts every installed plugin with an update regardless of the active search filter, so the count stays stable while typing. Installed plugins are also sorted case-insensitively now.

Motivation

Good to have search to find plugins easily and better for the people with many plugins installed.

Type of Change

• Bug fix
• New feature
• Breaking change
• Refactoring
• Build / packaging

Related Issue

Closes #4191

Testing

• just format && just test debug && just lint && python3 tools/i18n-check.py all ran with no issue

Manual Coverage

• Tested on Niri
• Tested on Hyprland
• Tested on Sway
• Tested on another compositor: Umbriel
• Tested with different bar positions and density settings
• Tested at different interface scaling values
• Tested with multiple monitors

Screenshots / Videos

recording_20260904_131250.mp4

Checklist

• This PR is ready for review, or it is marked as Draft.
• I read and followed the relevant guidance in CONTRIBUTING.md.
• I ran just format with clang-format v22+ installed, or this PR has no code changes.
• I ran the relevant build or test commands, or explained why they were not run.
• I self-reviewed the changes.
• I checked for new warnings or errors.
• I updated user-facing documentation in docs/user/ when this PR changes documented behavior or configuration, or this PR does not require documentation changes.
• I added or updated assets/translations/en.json, or this PR adds no new user-facing strings.
• I did not edit non-English translation files unless this PR is explicitly for translation tooling, an import/export sync, or a maintainer-requested locale change.
• I used the existing canonical names for config keys, IPC names, paths, and identifiers.

[github-actions]

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[github-actions]

The description now contains the required template structure.

[AdityaKr015]

Alrighty bot, I got it you want full line.