Separate group receipts from timestamps

[HANCORE-linux]

Summary

• Display a literal | between inline group receipts and their timestamp, e.g. Read by 1 | 13:05.
• Include the separator and both gaps in the width budget. Stack narrow metadata rows without a dangling separator.
• Preserve direct/incoming/system messages, timestamp text, and helper-authoritative receipt semantics.
• Extend the real-delegate layout regression, update the two reviewed QML source hashes without relaxing plaintext policy, and document the display behavior.

Validation

• Passed on the final tree: make test, make test-ci, sh tests/chat-transcript-layout.sh, python3 tests/qml_plaintext_test.py, qmllint pages/ChatPage.qml, omarchy plugin validate ., make arch, shell syntax, and git diff --check.
• Independent read-only review completed with no actionable findings; the committed patch matches the reviewed patch.
• Layout coverage includes live receipt transitions on the same delegate, missing timestamps, non-group and system rows, and widths just below, at, and above the full separator-inclusive requirement.

Limits

• Boundary tests set delegate width directly in the offscreen fixture. They do not validate native window resizing, parent Layout polish, or scrollbar feedback.
• Native Wayland acceptance of this separator remains pending. No live deployment or helper/service changes are included.
• make test-ci excludes the native Quickshell and Omarchy shell fixtures; the full local make test also passed.