[MG_Backend, docs] (P7): a wire decline's line says decline, not draw, because the texture rows count per sync

Fable review of the B3 rework, nit: MGL_WIRE_DECLINE_AT logged "Magma wire
draw declined [Site]" from every site, but the Tex*, Shape* and Upload*
rows are reached through SyncTextureResourceByHandle, whose callers are not
only the draw/dispatch texture preparation: the descriptor resolver,
framebuffer attachments, CopyTexSubImage, mipmap generation and
CopyImageSubData each Fatal right after a failed sync, and texture
readback falls back to the unbacked shadow. Those counters are per sync,
not per draw - a draw sampling three unsyncable textures counts three, a
failed attachment sync counts once and is then a Fatal.

- WireDeclineTally.h: the line is "Magma wire decline [Site]: ...", and
  the macro's comment says the texture rows are per sync and names the
  callers. Disaggregated-only header; no test or script matches the old
  text (git grep).
- magma-b3.md §1.5: says the counters are per sync and that the log lines
  quoted in §1.3 / §1.5 carry the old wording.

MobileGL/MG_Backend/DirectVulkan/Renderer/WireDeclineTally.h

@@ -150,11 +150,19 @@ private:
 
 // Every decline goes through this: the tally moves ALWAYS, the log line is once per site.
 // `return MGL_WIRE_DECLINE_FALSE(Site, "why", ...)` reads as the statement it replaces.
+//
+// A DECLINE IS NOT ALWAYS A SKIPPED DRAW, so the line does not say "draw". The Tex*, Shape* and
+// Upload* rows are counted per texture SYNC: SyncTextureResourceByHandle is reached from the
+// draw/dispatch texture preparation, but also from the descriptor resolver, framebuffer
+// attachments, CopyTexSubImage, mipmap generation and CopyImageSubData - each of which Fatals
+// right after a failed sync - and from texture readback, which falls back to the unbacked
+// shadow. A draw that samples three unsyncable textures counts three; a failed attachment
+// sync counts once and is then a Fatal, not a skipped draw.
 #define MGL_WIRE_DECLINE_AT(site, fmt, ...)                                                                            \
     do {                                                                                                               \
         ::MobileGL::MG_Backend::DirectVulkan::WireDeclineTally::Count(                                                  \
             ::MobileGL::MG_Backend::DirectVulkan::WireDeclineSite::site);                                              \
-        MGLOG_E_ONCE("Magma wire draw declined [" #site "]: " fmt, ##__VA_ARGS__);                                     \
+        MGLOG_E_ONCE("Magma wire decline [" #site "]: " fmt, ##__VA_ARGS__);                                           \
     } while (0)
 
 } // namespace MobileGL::MG_Backend::DirectVulkan