Initial commit: ASCILINE YouTube Streamer

ASCII-art YouTube streaming for the Tesla in-car browser.

- FastAPI server on a Mac mini, no Docker.
- yt-dlp resolver: ID/URL/search.
- ffmpeg with -re -fps_mode cfr for source-paced video; trivial drain
  consumer.  Separate ffmpeg for AAC/ADTS audio.
- Vendored ASCILINE renderer (MIT) for the binary wire protocol; pure
  fillText color path, on-demand selection flush.
- HMAC PIN-gated cookie; Secure flag scheme-aware so /audio works on
  plain http during local dev.
- LOW preset (120x50 24fps) verified clean on M4: FPS 24/24, JIT ~42ms.

config.py

@@ -0,0 +1,33 @@
+"""Quality presets and server defaults.
+
+Preset change requires re-Play (server restarts ffmpeg with new scale).
+"""
+
+PRESETS = {
+    "low": {
+        "cols": 120,
+        "rows": 50,
+        "fps_cap": 24,
+        "mode": 2,          # 512 colors
+    },
+    "med": {
+        "cols": 160,
+        "rows": 68,
+        "fps_cap": 30,
+        "mode": 3,          # 32K colors
+    },
+    "high": {
+        "cols": 200,
+        "rows": 84,
+        "fps_cap": 30,
+        "mode": 3,          # 32K colors
+    },
+}
+
+DEFAULT_PRESET = "low"
+
+SERVER_DEFAULTS = {
+    "port": 8000,
+    "bind": "0.0.0.0",
+    "max_source_height": 720,
+}