ci: add fast and full PR validation lanes

[Shahroz16]

Summary

• keep representative unsigned Android and iOS Release sample builds on routine PRs
• move FCM redundancy, signed distribution, and scene E2E to ci:full
• remove duplicate feature-branch push runs while preserving main and release callers
• isolate unrelated label events so they cannot cancel a requested full run

Validation

• TypeScript, 3 Jest suites / 17 tests, and npm pack --dry-run passed
• Android assembleRelease passed, including release bundling, R8, lint-vital, and packaging
• iOS unsigned Release simulator build passed across the 128-target CocoaPods graph
• changed workflow YAML passes differential Actionlint validation
• no release workflow changed

[github-actions]

Sample app builds 📱

Below you will find the list of the latest versions of the sample apps. It's recommended to always download the latest builds of the sample apps to accurately test the pull request.

---

Builds are in progress. This comment will be updated when they finish.

• iOS APN: 649.1.0 (29800377)
• iOS FCM: 649.1.0 (29800377)