initial seed: retrofit campaign lineage from local working trees

panvk-bifrost campaigns (r1..r4 Vulkan compositor + r5.video1 Vulkan
video decode) shipped before this repo existed; the deliverable
patches live in marfrit-packages, but the reasoning chain, phase docs,
and source-state evidence lived only in local working trees on the
development host.

This retrofit imports:
- mesa-panvk-bifrost/   — r1..r4 era phase docs (iter1..iter18)
                          (libmali stub blobs at iter18/blob/ excluded
                          — 109MB of RE artifacts replaced with a README
                          pointer)
- mesa-panvk-bifrost-video/ — sibling campaign phase docs + probe
- evidence/             — frozen .tgz source snapshots at each milestone
                          (basis for the 0005 patch diff generation)

Future iterations should branch off here from day one, so each iter is
a commit rather than a snapshot. See [[feedback-session-local-process-pins]]
for the process drift this retrofit closes.

Total: 1.9 MB across 124 files.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

mesa-panvk-bifrost/iter3/probe_triangle.vert

@@ -0,0 +1,13 @@
+#version 450
+
+// iter3 fullscreen triangle vertex shader.
+// Emits 3 vertices from gl_VertexIndex that cover NDC -1..1 with one big triangle.
+//   idx=0: NDC (-1,-1)   — top-left in Vulkan
+//   idx=1: NDC ( 3,-1)   — far-right (off-screen)
+//   idx=2: NDC (-1, 3)   — far-bottom (off-screen)
+// The visible portion of the triangle covers the full viewport.
+
+void main() {
+    vec2 pos = vec2((gl_VertexIndex << 1) & 2, gl_VertexIndex & 2);
+    gl_Position = vec4(pos * 2.0 - 1.0, 0.0, 1.0);
+}