Initial commit: GnommoEditor video pipeline

A code-first, declarative video editing system that compiles text
documents into rendered video via FFmpeg. Uses a compiler-style
ETL pipeline: Extract (parse inputs) → Validate → Transform
(build timeline) → Render (FFmpeg).

Features:
- Text-based project definition (manuscript, transcript, JSON configs)
- Slide markers [S1], [S2] in transcript map to timed overlays
- Strict validation with fail-fast error reporting
- FFmpeg filter_complex generation with time-based enables
- CLI with validate/render/dry-run modes

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

example/manuscript.txt

@@ -0,0 +1,5 @@
+Welcome to GnommoEditor, a code-first video editing system. [S1]
+
+In this example, we demonstrate how slides appear at specific timestamps based on markers in the transcript. [S2]
+
+And that's the end of our demo.