[MG_Pipe, MG_Impl, MG_State, MG_Remote, MG_Backend, MG_Test] (Disaggregated): P5e sb - set_shader_buffers is emitted, routed and applied

- MGPShaderBuffers::WritableMask is Uint32[3] and the POD grows 32 -> 40 (ID-104). One
  Uint32 could describe only the first 32 of an 84-point window, so a storage buffer bound
  at point 32 or above read as unwritable with nothing able to see it; the ruling widens the
  field rather than narrowing the window, which would change what an application may bind.
  MGPipeShaderBufferMaskHas / ...Set are the one spelling of the mask, so the emitter, the
  applier and the four backend sites cannot disagree about which word a point lives in.
- MGPipeApplySetShaderBuffers has its body: per-class window, Start/Count validated against
  the capacity, the mask copied by word, ONE ShaderBuffersSerial advanced on every applied
  record and ADVANCED - never zeroed - by both resets, which also clear the three windows.
- Route rows for opcode 38 on both arms (Mono_ and Wire_) and the server sink in the wire
  codec's decode switch, which is where a kCtxState row's sink lives - PipeApplier.cpp's
  ServerVerbSink has no method for it and the brief's "OnSetShaderBuffers" names no code.
  The codec also bounds Class and Start+Count where Count becomes a byte length.
- New MG_Impl/Pipe/ShaderBufferEmit.h: one record per class, window = the touched
  high-water mark clamped to 84, zero early-out before any hash, a BASE binding travelling
  as kMGPipeWholeBuffer so the server re-resolves the extent at use, three suppressor slots
  (ruling 11), and the writable mask that replaces the backend's GPU-write walk.
- BufferState gains a per-target bind-point generation (push-only, G1) and dirty bits
  15/16/17 shutter on it instead of the buffer CONTENT aggregate. That aggregate answered
  the wrong question in both directions: any glBufferSubData fired all three, and
  glBindBufferBase fired none of them, because it mutates a binding point through a returned
  reference. Same defect class as P4a's glBindSampler hole.
- Init.cpp publishes consumer bit 13 for DirectGLES and not for Magma (ID-106), in the same
  commit as the wired constant, and PipeFill's liveness gate asks R-8 for bit 13 in
  particular plus bit 13-requires-bit-7.
- `Touch` joins the dirty-surface scanner's mutator prefixes; TouchBufferBindingPoint gets
  its row and SetNamedTransformFeedbackBinding's is rewritten now that bit 17 reads a
  generation a binding moves. Negative control 6 is re-pointed: the pair it used to refute
  is a live answer, and a control that has quietly become positive is what the self-test is
  for.

MobileGL/MG_Backend/Init.cpp

@@ -97,9 +97,21 @@ namespace MobileGL::MG_Backend {
         // rather than aborting.
         constexpr Bool kMGPipeP5eRunAheadReady = false;
 
+        // P5e (sb, ID-106). DirectGLES GAINS BIT 13 - the indexed buffer binding points - and
+        // Magma deliberately does not. c0e landed the phase constant and the dirty-bit map with
+        // this row still reading P4a's mask, because withholding a consumer bit is the safe
+        // direction while no emitter exists: the client's R-8 gate then keeps the whole family
+        // on the legacy pull path. The moment ShaderBufferEmit.h's wired constant leaves 0 the
+        // two have to move together, so they are one commit.
+        //
+        // DIRECTVULKAN STAYS ON P4a's MASK. The bit says "this server reads set_shader_buffers
+        // instead of walking the client's binding-point table", and Magma's UniformManager does
+        // no such thing - it has no binding-point records at all, and P5e leaves it lockstep
+        // (CONTRACT-P5E.md §6). Claiming the bit there would make the client emit a family
+        // nothing consumes, which is ID-39's failure with a different family's name on it.
         Uint64 ConsumedSubsystemsFor(BackendType type) {
             switch (type) {
-            case BackendType::DirectGLES: return MG_Pipe::kMGPipeSubsystemsMigratedAtP4a;
+            case BackendType::DirectGLES: return MG_Pipe::kMGPipeSubsystemsMigratedAtP5e;
             case BackendType::DirectVulkan:
                 return MG_Pipe::kMGPipeSubsystemsMigratedAtP4a & ~MG_Pipe::kMGPipeSubsystemResources;
             default: return 0;