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.

example/project.json

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

example/slides.json

@@ -0,0 +1,10 @@
+{
+  "S1": {
+    "image": "S1.png",
+    "type": "square"
+  },
+  "S2": {
+    "image": "S2.png",
+    "type": "square"
+  }
+}

example/transcript.csv

@@ -0,0 +1,8 @@
+t,word
+0.00,Hello
+0.30,world
+0.60,[S1]
+1.50,Second
+1.80,slide
+2.00,[S2]
+2.50,End

example/videos.json

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+{
+  "talking_head": {
+    "file": "media/talking_head.mp4",
+    "preprocess": []
+  }
+}