Unify Iron Coast mission names and cinematic mission previews

mods/iron_coast_mission_4/art/briefing-sd-full-rgb-provenance.json

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+{
+  "purpose": "Full RGB SD briefing for the menu; replaces inherited palette posterization",
+  "source": "briefing_hd.png",
+  "source_sha256": "cd987c13bc55bba2620379ca435c0cccf08d7564364d730c65d0be285bb82221",
+  "old_sd_sha256": "11c8b492cd2df36ff05eeccded9a398da4af9113194b355fb4c6630f196d167d",
+  "sd_sha256": "9bd490c5c341303bea69f55bc323f5cced581d64740371703f70d3e7a1012256",
+  "recipe": "rebuild_briefing_sd.py",
+  "method": "RGB 320x200 Lanczos downsample of unchanged approved HD; no image generation",
+  "scope": "Menu illustration only; gameplay terrain, sprites, missions and audio unchanged"
+}

mods/iron_coast_mission_4/art/rebuild_briefing_sd.py

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+#!/usr/bin/env python3
+"""Refresh only this menu briefing SD image; gameplay artwork is untouched."""
+from pathlib import Path
+import hashlib
+from PIL import Image
+root = Path(__file__).resolve().parent
+source = root / "briefing_hd.png"
+assert hashlib.sha256(source.read_bytes()).hexdigest() == "cd987c13bc55bba2620379ca435c0cccf08d7564364d730c65d0be285bb82221", "Unexpected HD briefing"
+with Image.open(source) as image:
+    image.convert("RGB").resize((320,200), Image.Resampling.LANCZOS).save(root / "briefing_sd.png")