Add remastered OGV cutscene playback with MIDI music sync

[elliotttate]

Summary

• Adds support for playing the remastered OGV (Ogg Theora) video cutscenes from the Dark Forces Remaster, with the original iMUSE MIDI music synchronized to match
• Pre-scans the original FILM cutscene chain to extract CUST actor cue points and their timestamps, then scales them to OGV duration so MIDI transitions fire at the correct visual moments for all cutscenes
• Includes SRT subtitle support with the existing accessibility/caption system, OGV audio mixing alongside MIDI, and a user-facing toggle in the settings UI
• Builds are gated behind ENABLE_OGV_CUTSCENES (CMake) / preprocessor define so it has zero impact when disabled

Details

• New files: ogvPlayer.cpp/h (Theora/Vorbis decoding + OpenGL YUV rendering), remasterCutscenes.cpp/h (OGV path resolution from remaster install), srtParser.cpp/h (subtitle loading)
• Modified: cutscene.cpp (OGV playback path + FILM-driven cue scheduling), audioSystem (PCM mixing for OGV audio), renderBackend (fullscreen quad for video frames), settings (remaster cutscene toggle), frontEndUi (settings checkbox)
• CMakeLists.txt adds optional theoradec, ogg, vorbis dependencies behind the option flag
• vcxproj updated for Windows builds with bundled ogg/theora/vorbis libs

Test plan

• Play intro cutscene (scene 10) — music should start and transition at the same moments as the original LFD cutscene
• Skip cutscene with ESC/Space/Enter — music should stop, no leftover state
• Play with remaster cutscenes disabled in settings — original LFD path should be unaffected
• Build without ENABLE_OGV_CUTSCENES — should compile cleanly with no OGV code included
• Build on Linux with CMake + the theora/ogg/vorbis packages installed

[elliotttate]

Update: DCSS-driven cutscenes + hardening + docs

Significant follow-up work pushed to this branch:

What changed

• Replaced the FILM pre-scan entirely with a real DCSS parser. DCSS is the remaster's per-scene text script (lives in DarkEX.kpf at cutscene_scripts/<scene>.dcss) — I pulled the actual files out, matched the remaster's parser byte-for-byte (including the parse quirks like 00:00:58:827 and 00:1:50,487), and verified all 13 stock scripts parse identically. This also resolves @ifeldshteyn's comment about the missing getDuration() — that call went away with the rest of the scaling math.
• Dispatch against the video's intrinsic clock, not wall-clock, so music cues stay locked to the visible frame when the game hitches. Measured drift over full logo.ogv: 0–33 ms, bounded, no accumulation.
• Fixed musicvol: scale — was dividing by 127 (made every cutscene ~20% quiet), now divides by 100 to match the CUTSCENE.LST convention and the LFD path at cutscene_player.cpp:151.
• Parser hardening: sorted-on-load (defensive against hand-edited DCSS), # / // comment support, bounded string parsing, tolerant of locale typos.
• Locale-aware file lookup: logo_de.ogv, arcfly_de.srt etc. (matches remaster's convention).
• Merged master — picks up @luciusDXL's FileUtil::directoryExists rename from Fixing FileUtil exists check for windows. updating directoryExists ca… #590.

New documentation

Six markdown files under TheForceEngine/Documentation/markdown/remaster-cutscenes/:

• README.md — overview + quick starts
• architecture.md — pipeline diagram, path resolution, dispatch loop rationale, stock cutscene.lst reference
• dcss-format.md — complete format spec with stock annotated examples
• modding-guide.md — end-to-end walkthrough
• video-conversion.md — verified MP4 → OGV ffmpeg command lines (tested end-to-end with a 30s clip + hand-written DCSS, 3/3 cues fired with 0ms video drift)
• troubleshooting.md

Verification

• Debug + Release builds clean (Windows v143, SDK 10.0.26100.0).
• Full logo.ogv (1:53, 5 DCSS cues) played end-to-end under the DCSS_TIMING_TRACE instrumentation; see commit message for the drift table.
• Parser regression suite: 5 edge cases (stock files, unsorted, comments, truncated, empty buffer) — all pass.

Tracing flag DCSS_TIMING_TRACE in cutscene.cpp ships disabled; flip to 1 for per-cue drift logs when authoring new DCSS files.