Multi View Phase 2

[owens1127]

• Allow editing multi views (name & instance)
• Increase parity with pgcr viewer
• bug fixes

[owens1127]

Closed via #319 — multi-instance PGCR now uses the standard PGCR UI (PGCRHeader, PGCRPlayers, player details panel, query params) with a session timeline for 2+ instances.

Verified locally: merged view renders correctly, timeline shows both instances, and reporting is hidden for merged sessions.