feat: add live SABR media support

[Priveetee]

Summary

• add live playback window contracts and dynamic MediaSource timing
• follow the live edge while preserving DVR seeks
• recover stalled live windows without unbounded buffering
• extend buffering during transient live gaps
• publish the tested MSE contract as 0.1.35 on npm and JSR

Runtime verification

• validated @typetype/mse 0.1.35 through the TypeType beta frontend
• validated Chromium, Firefox and WebKit on the watch page and embed
• observed a continuous live session for about 22 minutes with bounded server-side media caching
• live quality and codec switching remains tracked separately in [Bug]: Live playback freezes after changing quality or codec TypeType#163

Tests

• bun run check
• bun run check:versions
• bun run check:docs
• bun run check:jsr
• bun run test:coverage
• bun run build
• git diff --check
• CI workflow