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.frag

@@ -0,0 +1,21 @@
+#version 450
+
+// iter3 gl_FragCoord-encoded fragment shader.
+// For each pixel at integer position (x, y):
+//   R = x / 255    -> byte x   (UNORM)
+//   G = y / 255    -> byte y   (UNORM)
+//   B = 0x80       -> sentinel proving the frag shader executed
+//   A = 0xff       -> opaque
+// Readback: pixel at (col, row) should be 0xff80(row)(col) LE.
+
+layout(location = 0) out vec4 outColor;
+
+void main() {
+    uvec2 ipos = uvec2(gl_FragCoord.xy);
+    outColor = vec4(
+        float(ipos.x) / 255.0,
+        float(ipos.y) / 255.0,
+        128.0 / 255.0,
+        1.0
+    );
+}