Cycle 5 closed: CDEF QPU R5=0.116 ORANGE, opportunistic helper

Phase 4 plan with 3 Phase-5 REDs applied inline:
  - meta layout: m.z=tmp_off, m.w=dir
  - sec_shift clamped to >=0 (NEON uqsub semantics)
  - directions table as const ivec2[14], not OR-packed

Phase 6 deliverable: v3d_cdef.comp (387 inst, 2 threads, no spills).
3-way M1 (QPU vs C ref vs NEON) PASS 4096/4096.

M2: 0.443 Mblock/s -> R5 = 0.116 ORANGE (predicted 0.02-0.05 RED).
M4 same-kernel: NEON-3+QPU 8.46 < NEON-4 alone ~10 (negative).
M4 mixed (NEON-3 MC + QPU CDEF): CPU 34.17 Mblock/s MC,
  QPU 0.42 Mblock/s CDEF helper. CPU side higher than the
  Issue 003 NEON-fallback proxy suggested - cross-substrate
  contention is gentler than same-side NEON contention.

Verdict: CDEF stays on CPU; QPU dispatch path exists for
opportunistic use. Deployment recipe table updated for all 5
cycles. Phase 9 lessons: linear extrapolation across cycles is
too pessimistic; CDEF is bandwidth-bound on NEON despite high
per-block ns; real-substrate-cross contention < NEON-proxy
contention.

- src/v3d_cdef.comp: cycle 5 QPU shader
- tests/bench_v3d_cdef.c: 3-way M1, M2 bench
- tests/bench_concurrent_mixed.c: K_CDEF on both sides
- tests/cdef_ref.c + bench_neon_cdef.c: sec_shift clamp +
  expanded damping range to exercise the edge case
- CMakeLists.txt: v3d_cdef.spv + bench_v3d_cdef wiring
- docs/k5_cdef_phase4.md updated with Phase 5 review applied
- docs/k5_cdef_phase7.md: closure doc with full verdict matrix

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/bench_neon_cdef.c

@@ -79,12 +79,17 @@ static void gen_filter_params(int *pri, int *sec, int *dir, int *damping)
      *   pri_strength: 1..7 (non-zero for combined path)
      *   sec_strength: 1..4
      *   dir:          0..7
-     *   damping:      3..6
+     *   damping:      1..6 — extended down to 1 (was 3..6) per
+     *                 cycle 5 phase 5 RED-2: include cases where
+     *                 sec_shift = damping - ulog2(sec) goes negative
+     *                 (e.g. damping=1, sec=4 → sec_shift = -1).
+     *                 Both NEON (uqsub) and C ref (now max(0,...))
+     *                 saturate to 0 here; the bench should exercise it.
      */
     *pri     = (int)(xs() % 7) + 1;
     *sec     = (int)(xs() % 4) + 1;
     *dir     = (int)(xs() & 7);
-    *damping = (int)(xs() % 4) + 3;
+    *damping = (int)(xs() % 6) + 1;
 }
 
 static double now_seconds(void)