Story 4.9: Apply Slide Metadata (Transitions, Hidden) in Viewer

[ajelinek]

Part of #10

As a user, I want the presentation viewer to respect metadata associated with slides, such as custom transitions between slides or marking certain slides as hidden from the main sequence.

Acceptance Criteria:

• If a slide has a transition specified in its metadata, that transition effect is used when navigating to/from it.
• If a slide is marked as hidden: true, it is skipped during normal next/previous navigation but may still be accessible via direct link or overview mode (TBD).
• Other metadata (e.g., slide title) is used appropriately (e.g., in breadcrumbs, overview).

Test Cases:

• E2E test: A specified slide transition (e.g., "fade") is observable.
• E2E test: A hidden slide is skipped during linear navigation.
• E2E test (if hidden slides are accessible): Navigate to a hidden slide via a direct link/overview.

Constraints:

• Transition effects might require CSS animations/transitions or a small JS library.
• Defining behavior of "hidden" slides (fully inaccessible vs. accessible via other means) is crucial.

Dependencies:

• Story 1.3 (Support for Optional Slide Metadata).
• Story 3.2 (Extract Slide Metadata).
• Story 4.3 (Core Navigation Controls).