Support f-children element filters

[pradeep-ramola]

Pull Request

📖 Description

Updates the declarative template parser so f-children supports the same filter elements(...) syntax that f-slotted already supports.

Previously, f-children="{childItems filter elements()}" treated the whole string as the property name. Now it resolves to children({ property: "childItems", filter: elements() }).

🎫 Issues

Fixes #7631

👩‍💻 Reviewer Notes

The parser now shares node directive option parsing between children() and slotted(). Existing f-slotted behavior is preserved.

📑 Test Plan

Tested locally with:

• npx playwright test src/declarative/template-bridge.pw.spec.ts --project=chromium
• npm run build:tsc -w @microsoft/fast-element
• npm run lint -w @microsoft/fast-element
• npx beachball check --branch origin/main

Note: Firefox/WebKit Playwright browsers are not installed locally, so the all-browser run could not complete. Chromium passed.

✅ Checklist

General

• I have included a change request file using $ npm run change
• I have added tests for my changes.
• I have tested my changes.
• I have updated the project documentation to reflect my changes.
• I have read the CONTRIBUTING documentation and followed the standards for this project.

Agents

• I have linked to an existing issue in this project that this change addresses
• I have read the skills
• I have read the DESIGN.md file(s) in packages relevent to my changes
• I have updated the DESIGN.md file(s) in packages relevent to my changes

⏭ Next Steps

No follow-up work is planned for this PR.

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