AA: catalog growth — S7F1/F17, S6F5-F22, S2F21, S12F9-F18

Adds the SECS-II messages secsgem-py 0.3.0 ships but our C++ catalog
didn't have, plus the alternative wafer-map formats from E5 §13.
None of these were strictly required for GEM core compliance, but
they're the messages a host might send to a conformant equipment.

  * S7F1/F2 — Process Program Load Inquire / Grant.  Equipment-side
    space-and-policy check before a host commits to S7F3.
  * S7F17/F18 — Delete Process Program.  Empty list = delete-all.
  * S6F5/F6 — Multi-block Data Send Inquire / Grant (with MultiBlockGrant
    enum: Ok/Busy/NoSpace/DuplicateMsg/BadMsg).
  * S6F7/F8 — Data Transfer Request / Send.  Host pulls a DATAID;
    equipment replies with the nested DS/DV structure.
  * S6F15/F16 — Event Report Request (host-initiated).  Reply mirrors
    the unsolicited S6F11.
  * S6F19/F20 — Individual Report Request (RPTID -> values).
  * S6F21/F22 — Annotated Individual Report Request (RPTID -> (VID, value)).
  * S2F21/F22 — Legacy Remote Command (no parameter list).  Delegates
    to the same HostCommandRegistry as S2F41.
  * S12F9/F10 — Map Data Send (array format, MAPFT=1).
  * S12F11/F12 — Map Data Send (coordinate format, MAPFT=2).
  * S12F13/F14, F15/F16, F17/F18 — Map Data Request variants for the
    row, array, and coordinate formats.

11 new round-trip tests; suite at 289 cases / 1495 assertions.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

include/secsgem/gem/messages_helpers.hpp

@@ -2,7 +2,6 @@
 
 #include <cstdint>
 #include <functional>
-#include <limits>
 #include <optional>
 #include <string>
 #include <variant>
@@ -233,6 +232,17 @@ enum class EventReportAck : uint8_t {  // S6F12
   Denied = 1,
 };
 
+
+// S6F6 GRANT6.  Permission byte for equipment-initiated multi-block
+// (S6F5 inquire).  Codes from SEMI E5.
+enum class MultiBlockGrant : uint8_t {
+  Ok            = 0,
+  Busy          = 1,
+  NoSpace       = 2,
+  DuplicateMsg  = 3,
+  BadMsg        = 4,
+};
+
 enum class TerminalAck : uint8_t {  // S10F2, S10F4
   Accepted = 0,
   WillNotDisplay = 1,