[Refactor] (Pipe, State): extract MGPipeValueTypes.h - move the render-state, sampler and vertex value types and their enums out of MG_State/GLState so MG_Pipe no longer reaches RenderState.h; pure move, member order and namespaces unchanged

- ROADMAP P0.5 / ARCHITECTURE.md value-header manifest: MGPipeTypes.h embedded
  RenderStateParameters and PixelStoreParameters through RenderState.h, which drags
  FramebufferObject.h and the whole texture/renderbuffer/sampler chain into MG_Pipe;
  purity gate A (no MG_State/MG_Impl/MG_Backend/MG_Remote in the closure) could not
  be armed for anything in MG_Pipe while that include existed.
- MGPipeValueTypes.h is a verbatim cut, comments included: the eleven RenderState.h
  enums (all of them - a split would be the maintenance trap), PixelStoreParameters,
  PerBufferBlendState, StencilFaceState, RenderStateParameters (member order
  untouched: DirectGLES' offsetof spans and PipeSpanTable.inc name the members),
  the six SamplerObject.h enums and SamplerParameters (BorderColorForm stays Uint8,
  it sets the tail padding), and VertexAttribute / VertexBufferBindingPoint /
  VertexAttributeVersion, which keep namespace MobileGL::MG_State::GLState with a
  forward-declared BufferObject so no mangled name changes.
- MAX_DRAW_BUFFERS becomes inline constexpr kMGMaxDrawBuffers in namespace MobileGL
  and FramebufferObject::MAX_DRAW_BUFFERS is defined from it, so the eighty existing
  spellings keep working and the two cannot drift. No other constant is added.
- The four MG_State headers become forwarders (include the value header, keep their
  class definitions); RenderState.cpp gains a direct FramebufferObject.h include
  because it spells FramebufferObject::MAX_DRAW_BUFFERS and only ever got that
  header transitively. No other TU lost a transitive include: the full build
  (Release, clang, tests + integration tests) passed without touching anything
  under MG_Backend, MG_Impl or MG_Util.
- DynamicBackendParameters does NOT move (SizeT members and TextureTarget-taking
  member functions make that a type change, not a move); MGPipeTypes.h keeps its
  BackendObject.h include and the debt comment now says so, which is why gate A
  asserts MGPipeValueTypes.h rather than MGPipeTypes.h.
- New trip wires in the header: trivially-copyable + exact sizeof for
  PixelStoreParameters/PerBufferBlendState/StencilFaceState (28), SamplerParameters
  (100), VertexAttributeVersion (6), RenderStateParameters (1168, standard layout,
  BlendStates before LogicOp, BlendStates sized by kMGMaxDrawBuffers). Their runtime
  twins ValueTypeLayoutsArePinned and the carrier check
  ResidualBlockIsExactlyItsTwoValueStructsPlusPatchTail (Pack at 1168,
  CapabilityBits at 1200) are added to PipeCatalogueTest without a new include.
- gen_pipe.py's "field lists of their own in P0.5" comment now says P1 (the
  comparator needs std::array<struct> support first); PipeVerify.inc regenerated.
- Verified: ctest -L unit 1460/1460 and -L integration-gpu green; ctest -N names
  a superset of feat/disaggregated@6672778b (two added, none lost); one definition
  per moved type; the -H closure of the new header contains no MG_State/MG_Backend/
  MG_Impl/MG_Remote header and the header compiles alone; nm --defined-only -S
  against the base libMobileGL.so: 0 added / 0 removed / 0 resized, .text
  byte-identical, the only differing bytes are the build-id and two stamp strings.

scripts/gen_pipe.py

@@ -161,8 +161,9 @@ def parse_calls():
 
 
 # The member types the G4 comparator falls back to memcmp for (see gen_verify): the
-# MG_State / MG_Backend value structs and MGHostSpan. They are not call payloads and get
-# field lists of their own in P0.5. Nothing else may be missing from PipeFields.def.
+# MG_Pipe / MG_Backend value structs and MGHostSpan. They are not call payloads and get
+# field lists of their own in P1 (P0.5 moved the types). Nothing else may be missing from
+# PipeFields.def.
 MEMCMP_FALLBACK_TYPES = {
     "RenderStateParameters",
     "PixelStoreParameters",
@@ -407,11 +408,11 @@ inline Bool MGPipeFieldEqual(const T& a, const T& b) {
     } else if constexpr (requires(const T& x, const T& y) { x == y; }) {
         return a == b;
     } else {
-        // MEMCMP FALLBACK. Only reached by the payload members that are still MG_State /
-        // MG_Backend value structs (RenderStateParameters, PixelStoreParameters,
-        // DynamicBackendParameters) and by MGHostSpan. Those are exactly the types P0.5
-        // moves into MGPipeValueTypes.h, at which point they get field lists of their own
-        // and this branch stops being reachable from any payload.
+        // MEMCMP FALLBACK. Only reached by the payload members that are still value structs
+        // without a field list (RenderStateParameters, PixelStoreParameters,
+        // DynamicBackendParameters) and by MGHostSpan. P0.5 moved the first two into
+        // MGPipeValueTypes.h; P1 gives them field lists of their own, at which point this
+        // branch stops being reachable from any payload.
         return std::memcmp(&a, &b, sizeof(T)) == 0;
     }
 }