[MG_Backend, MG_State, MG_Pipe, MG_Remote, MG_Impl, MG_IntegrationTest, docs] (P7): magma installs a state-object death table, and the inproc arm stops losing every object_death

CONTRACT-P7 §5.5. DirectVulkan had no StateObjectDeathOps at all, so under a Magma
inproc session NotifyStateObjectDestroyed reached nobody and the server was never told
that a frontend object had died. Package L measured the shape: with the WireTables
install condition made backend-agnostic, CtWireScenario's two death cases PASS on Magma
spawn and tcp - the remote client has no local backend, so the client-side emitter
installed there answers the notice - and FAIL on inproc, where the install condition
deliberately stands aside for "the backend's own dispatcher" and Magma had none.

g_magmaStateObjectDeathOps is that dispatcher. It mirrors g_glesStateObjectDeathOps
(DirectGLES/Managers.cpp:335) with ONE arm rather than two: Espryt's other arm destroys
a backend twin keyed by lifetime id, and Magma keeps no such twin - its two
client-minted kinds are keyed on {slot, gen} by MagmaPipeIdentityTables and the other
six are still reached from their frontend objects - so what is left is exactly the emit
of object_death off the apply thread. Installed from
BackendObject_DirectVulkan::Initialize(), i.e. ServerLoop::CreateBackend, step 1 of
InitServerRoleCommon: the one place BOTH Magma server roles pass through, and before any
client session exists. #if MOBILEGL_BUILD_DISAGGREGATED && MOBILEGL_PIPE_PUSH, so the
pull build compiles nothing new.

The two skip guards in CtWireScenario go with it. Every other "Magma installs none" site
the audit found is comment text whose ARGUMENT survives, and each is reworded rather than
deleted: the table emits the wire record and frees no client slot, so P4a's
backend-neutral NotifyAndFree is still the only thing that returns one, HandleRecycle's
C-1 case still measures the only protection the allocator has, and MagmaPipeArms' age
sweep is still the only thing that retires an identity slot.

The framebuffer death case now reads the client's allocator beside the server's tally.
That correction matters: the plan called this a slot leak provable with PipeSlotPeek, and
it is not - it has been backend-neutral since P4a. What leaked was the SERVER's twin, and
a framebuffer has no wire delete opcode at all, so object_death is its only delivery.

Two installers cannot race although the global is last-writer-wins with no stacking:
Magma's runs only in a process that owns a DirectVulkan backend, and
InstallClientWireTables' arm runs only under Transport == Spawn, which is by construction
the process that owns none.

RED-ONCE: `if (false) InstallStateObjectDeathOps();` reds the two Split cases alone
(`Expected: (afterCounters.deaths) > (deathsBefore), actual: 0 vs 0`, CtWireScenario.cpp:264)
and leaves spawn and tcp green - the exact split of responsibility the comment claims.
Restored: 8/8. Recorded in docs/Disaggregated/notes/p7/magma-c.md.

MobileGL/MG_Backend/DirectGLES/Managers.cpp

@@ -307,8 +307,9 @@ namespace MobileGL::MG_Backend::DirectGLES {
                 // whole death itself (MGPipeEmitVertexElementsDestroyAndFree: delete the
                 // applier record, raise this notice, free the slot), because the slot is minted
                 // client-side on every backend and a backend that installs no death ops - which
-                // Magma deliberately does not - otherwise leaked the slot and the record per
-                // VAO for the life of the process. What is left here is the one thing only this
+                // Magma did not until P7 wave 2 package C, and whose table even now only EMITS
+                // the wire record - otherwise leaked the slot and the record per VAO for the
+                // life of the process. What is left here is the one thing only this
                 // side can do: drop the driver VAO the twin owns. It is raised while the handle
                 // still resolves, so OnFrontendObjectDestroyed's shared free (which the other
                 // five kinds still depend on) is simply the one that gets there first; the