[NUAAwqy]

What does this PR do?

Batch-pasted message properties separated only by carriage returns (classic Mac text and some clipboard flows) were swallowed into the previous value because the parser split on \r?\n only. The split now treats CR, LF and CRLF alike as record separators, and a new unit test covers mixed line endings.

Fixes #7106

[NUAAwqy]

The Backend Tests (Java 21) failure on this PR looks flaky, not caused by these changes.

• Out of 3834 backend tests, the single error is ResourceOwnershipGuardTest.migrationConcurrentStartupIsIdempotentTest, caused by a java.util.ConcurrentModificationException inside the embedded H2 engine (org.h2.engine.SessionLocal.addTableToDependencies) while the test runs schema migrations concurrently — a race in H2 session state, not in the code under test.
• This PR only touches frontend files (web/src/utils/messageProperties.ts + its test); no backend code is modified, and the frontend job is green.
• The baseline push run on rocketmq-studio @ 127c47b0 (https://github.com/apache/rocketmq-dashboard/actions/runs/39257998487) has Backend Tests passing, confirming this is intermittent.

I don't have permission to re-run the workflow from a fork (the API returns 404). Could a committer please re-run the failed job for run https://github.com/apache/rocketmq-dashboard/actions/runs/39276947373 ? Thanks!

[NUAAwqy]

The Backend Tests (Java 21) job failed here, but it passes on the base commit (127c47b0) and on the sibling PRs, and this PR only touches frontend TypeScript files (web/src/utils/messageProperties.ts + its test), so the failure looks unrelated / flaky. Could a maintainer re-run the failed job? Thanks!