fix: prepare server 1.2.4

[Priveetee]

Summary

• fix intermittent SABR initialization failures on resumed videos
• bound playback preparation when required media never becomes available
• treat completed livestreams as VODs during startup and format changes
• update PipePipeExtractor and align the Server version with TypeType 1.2.4

Production behavior

• resumed VOD playback no longer stays in an endless preparation loop
• completed livestream recordings no longer use the active live-edge path
• failed initialization returns a recoverable terminal state instead of recreating sessions indefinitely
• normal seeks and quality changes preserve the requested playback position
• no database migration or environment change is required

Runtime verification

• beta revision 07bd1cfae94815980df77264013f9b8bce2085ed
• confirmed the beta rollout before stable promotion
• covered initial playback and format replacement for historical livestream VODs

Tests

• ./gradlew test
• ./gradlew check
• ./gradlew shadowJar
• git diff --check
• focused stalled initialization and historical livestream tests

Rollback

• previous stable Server revision: 718ed47d4bfe8f1d2b2282dd833fa9a22e909849
• previous stable image: ghcr.io/typetype-video/typetype-server@sha256:4cb61c09bd31f156e51e1eabdc71cb197ad7290f99b81f895423369dbd1a92b5