D157: objective MinDificulty read at wrong byte on LE -> campaign never unlocks

ROOT CAUSE of 'complete Dam, Facility stays locked'. The type-23
objective record's MinDificulty is a big-endian s32 at word 3; on N64 the
value is its low byte == offset 0xF, and struct objective_entry reads
'difficulty' as s8 @0xF. d88_propdefs.py bswap32's word 3, so on
little-endian the value moves to offset 0xC -> objective_entry.difficulty
@0xF reads 0 for EVERY objective. get_difficulty_for_objective() then
returns Agent(0) for all, so objectiveIsAllComplete() on Agent evaluates
objectives that should be difficulty-gated out (Dam obj 0 'Neutralize all
alarms' is Secret Agent; obj 1/2 are 00 Agent) -> they're incomplete ->
never returns TRUE -> end_of_mission_briefing() / the unlock write never
runs. User was right: you don't touch an alarm on Agent Dam.

Fix (D151-class, #ifdef PORT): reorder struct objective_entry's word-3
tail so 'difficulty' reads @0xC (post-swap position); N64 layout kept
under #else. Also fixes dump_objectives.py (was reading byte 0xC = the
BE high byte = always 0; hence LEVEL-OBJECTIVES.md said 'Agent' for
everything). Dam now decodes obj0=Secret Agent, obj1/2=00 Agent,
obj3=Agent. -level_09 coverage identical (phash delta is the M-30 RC2
texture change, not this).

src/bondtypes.h

@@ -4055,13 +4055,21 @@ struct objective_entry
     enum WATCH_BRIEFING_PAGE menu;       // 4
 #ifdef PORT
     u32                      text;       // 8  (D151: full-word slot id, see above)
+    /* D157: the setup converter (d88_propdefs.py) bswap32's word 3 of the
+       type-23 record (MissionObjectiveRecord.MinDificulty).  On N64 (BE) the
+       difficulty is the low byte of that word == offset 0xF; after the swap it
+       lands at 0xC on LE.  N64 layout kept under #else. */
+    s8                       difficulty; // c
+    u8                       _md_b2;     // d
+    u8                       unkD;       // e  (N64 0xD, post-swap)
+    u8                       _md_b0;     // f
 #else
     u16                      reserved;   // 8
     u16                      text;       // a
-#endif
     u16                      unkC;       // c
     u8                       unkD;       // d
     s8                       difficulty; // f
+#endif
 };
 #pragma endregion Objectives
 

src/game/objective_status.c

@@ -299,12 +299,13 @@ OBJECTIVESTATUS get_status_of_objective(s32 objectiveNum) //#MATCH
 #ifdef PORT
                     if (g_savelogObjOnce && getenv("GE_SAVELOG")) {
                         u32 *rw = (u32 *)objective;
-                        osSyncPrintf("SAVELOG:     crit obj=%d type=%d ObjRefID=%d(0x%x) "
+                        osSyncPrintf("SAVELOG:     crit obj=%d type=%d ObjRefID=%d "
-                                     "TextID=0x%x stride=%d words=[%08x %08x %08x] curstat=%d\n",
+                                     "TextID=0x%x MinDif=%d stride=%d words=[%08x %08x %08x %08x] "
+                                     "curstat=%d\n",
                                      objectiveNum, (int)objective->type, (int)objective->ObjRefID,
-                                     (unsigned)objective->ObjRefID, (unsigned)objective->TextID,
+                                     (unsigned)objective->TextID, (int)objective->MinDificulty,
                                      (int)sizepropdef((PropDefHeaderRecord *)objective),
-                                     rw[0], rw[1], rw[2], (int)currentstatus);
+                                     rw[0], rw[1], rw[2], rw[3], (int)currentstatus);
                     }
 #endif
                     if (status == OBJECTIVESTATUS_COMPLETE)

tools_pc/dump_objectives.py

@@ -156,7 +156,9 @@ def dump_level(levelid, lav_name):
         nblocks += 1
         idx = bs32(buf, off + 4)
         textid = be32(buf, off + 8)
-        diff = buf[off + 12]
+        # MinDificulty is a big-endian s32 at word 3 (offset 0xC); the value
+        # lives in its low byte == offset 0xF.
+        diff = buf[off + 15]
         print(f"Objective {idx}  [briefing text id {textid}]  min difficulty: "
               f"{DIFF_NAMES.get(diff, diff)}")
         j = i + 1