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/project.json

@@ -0,0 +1,11 @@
+{
+  "resolution": [1920, 1080],
+  "fps": 30,
+  "talkinghead": {
+    "x": 50,
+    "y": 600,
+    "targetheight": 400
+  },
+  "defaultSlideType": "square",
+  "background_video": ""
+}