feat(slots): manage isolated browser animation projects

[DonIsmaelito]

Why

Browser-authored animations need a separate workspace and a checked render before they enter an edit. This adds a helper that creates and manages those animation slots.

Use this for product-launch videos, animated UI demos, kinetic typography and graphic transitions built with HTML, CSS, SVG and GSAP.

Changes

• Add reusable MotionKit components and an editable starter with a paused, seekable timeline.
• Create isolated projects with explicit dimensions, FPS and duration; record supplied assets with provenance.
• Invoke pinned HyperFrames checks and rendering, verify encoded dimensions, frame rate and frame count, and protect existing videos and reports.
• Three focused commits cover components, the slot helper and documentation. All 50 Python tests and 7 JavaScript tests pass; one optional browser test is skipped. MP4 verification and publication use real FFmpeg output in tests.

Limits

Requires separately provisioned HyperFrames 0.8.30, GSAP 3.15.0, a browser, FFmpeg and ffprobe. The helper never installs packages. Native HyperFrames rendering and browser seek checks remain untested in this environment.

Supports integer FPS and MP4 delivery. It does not automatically change an EDL, export transparent WebM or approve visual/audio quality. Asset records assume one writer; publication requires hard-link support and is not atomic across video and report.

This targets main independently and complements #13's engine-selection guidance and #129's environment checks. Unlike the specific outro workflow in #68, it creates reusable authoring workspaces. No third-party media, fonts or vendored engines are bundled; broader motion-design guidance remains deferred.