reference: commit the real-boot frame evidence (33MB) with a NOTES.md; gitignore the 201MB source recording

.gitignore

@@ -36,3 +36,9 @@ tools/ghidra-headless-mcp/
 
 # Generated harness logs
 harness/mame/board-*.log
+harness/mame/gui.log
+
+# Large media: the source recording stays out of git (a YouTube download,
+# trivially re-obtainable).  The derived frames and contact sheets ARE committed,
+# as evidence — see reference/vt1200-boot-video/NOTES.md for the regeneration recipe.
+video/

reference/vt1200-boot-video/NOTES.md

@@ -0,0 +1,46 @@
+# Real VT1200 boot recording — reference material
+
+Source: `video/DEC VT1200 Hardware X11 terminal boot and demo. [j_mJB3asDgE].mkv`
+(201 MB, **gitignored** — it is a YouTube download and trivially re-obtainable).
+
+Everything committed here is **derived** from it: contact sheets for navigation,
+full-resolution frames for detail.
+
+## Regenerating
+
+```sh
+V="video/DEC VT1200 Hardware X11 terminal boot and demo. [j_mJB3asDgE].mkv"
+# contact sheets: one frame per 2 s, 6x6 tiles
+ffmpeg -v error -y -i "$V" -vf "fps=1/2,scale=320:-1,tile=6x6" sheet_%02d.png
+# full-resolution frame at a chosen time — OUTPUT seek; input seek (-ss before -i)
+# fails on this filename with "Invalid argument"
+ffmpeg -v error -y -i "$V" -ss 26 -frames:v 1 real_t26.png
+```
+
+## The real boot timeline
+
+This is the ground truth the harness is compared against.
+
+| video time | what is on screen |
+|---|---|
+| 0:00–0:12 | **nothing** — the monitor's own blue no-signal backdrop |
+| ~0:13 | the terminal starts driving the display |
+| 0:14–0:44 | the self-test **pie / progress disc** sweeping to completion |
+| ~0:45 | wipe to black |
+| ~0:48 | a **dialog box** (the Terminal Manager) |
+| ~1:08 | a light (mostly white) screen |
+
+The harness reaches the X11 weave and the Terminal Manager via
+`VT1200_SKIP_LEVEL1=1`; on real hardware level 1 passes, so it goes further.
+
+## One correction kept deliberately
+
+The low-resolution contact sheets *appeared* to show a **text block** at ~0:14, and
+that was briefly reported as a real screen. A full-resolution crop
+(`real_text_crop.png`, taken at 0:14.2) shows the screen is **blank blue** — the
+monitor's no-signal state. The "text" was a scaling/compression artefact of a
+320-pixel tile.
+
+**A contact sheet tells you *when* something happens, not *what* it says.** Crop and
+up-scale before reading anything off one — the same class of mistake as concluding
+"it never paints" from a single frame.