Add separate Iron Coast mission, weapon and enemy mods with SD HD artwork and audio

examples/mods/iron_coast_turret/art-qa.json

@@ -0,0 +1,29 @@
+{
+  "logical_size": [
+    32,
+    32
+  ],
+  "hd_scale": 8,
+  "origin": [
+    0,
+    0
+  ],
+  "frames": 1,
+  "frame_order": [
+    "idle"
+  ],
+  "alpha": "Preserved RGBA; runtime uses alpha>=128 indexed transparency",
+  "registration": "Common full-canvas resize and equal padding for every frame",
+  "sources": [
+    {
+      "source": "art/unit-generated-v1.png",
+      "source_sha256": "37a7be58863d84028b01f67b133ae694d070cfe8155d939c0cbe81ca4ab621a7",
+      "sd_opaque_bounds": [
+        3,
+        2,
+        29,
+        30
+      ]
+    }
+  ]
+}