Cloud Playout channel creation flow

Cloud Playout channels can now be created end-to-end from a guided wizard inside the dashboard.

• Pick between Loop channel and Schedule channel up front; the rest of the wizard adapts to the choice.
• Programs are added via a media picker with private-media restrictions enforced based on the playback policy.
• Bumpers and segments (pre-roll, post-roll, mid-roll) can be configured during creation with duration limits clearly displayed.
• Overlays — including dynamic and looped overlays — are wired into the same flow so you don’t need a second pass to add branding.
• Channel state changes (activate, deactivate, draft) are surfaced as confirmation modals with the correct copy for each transition.

Calendars throughout the flow now share a single date-picker component, fixing a long list of timezone and outside-click bugs.