feat: A-frame tent + portal walk-through field + texture polish

- camping: replace cube tent with A-frame slope panels (tent_panel_l/r) +
  cardinal_direction permutations; vote-skip sleep that mixes
  player.isSleeping bed sleepers with tent occupants and respects the
  playersSleepingPercentage gamerule; new weathered-canvas texture.
- lobby: walk-through silverlabs:portal_field block (no collision,
  translucent swirl, cross-plane geo) auto-placed above each portal frame;
  invisible silverlabs:portal_label entity floats above each portal with
  the destination world name; transfer detection now scans down through
  the field to find the destination frame.
- postal: regenerate post_office and mailbox block textures so they fill
  the full block face (brick + POST plaque, full red panel with slot/latch
  /flag/rivets) instead of small sprites floating on transparent.
- dynamite + tow-boat: ship the addons (volumes wired into all four
  worlds; enabled_packs registers them into Mya's world).
- art: build-textures.py extended; build-art-catalog.py added to project.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tow-boat-addon/tow_boat_BP/manifest.json

@@ -0,0 +1,33 @@
+{
+  "format_version": 2,
+  "header": {
+    "name": "Tow Boat",
+    "description": "A flatbed boat that can be leashed and chained for towing.",
+    "uuid": "a35d89fd-99e1-497a-9e78-35443c0cd59f",
+    "version": [1, 0, 0],
+    "min_engine_version": [1, 21, 0]
+  },
+  "modules": [
+    {
+      "type": "data",
+      "uuid": "b29d967c-8a9a-491d-867d-2866890780f0",
+      "version": [1, 0, 0]
+    },
+    {
+      "type": "script",
+      "uuid": "06b92593-0c15-41a0-8f39-bc6bba516ebb",
+      "version": [1, 0, 0],
+      "entry": "scripts/main.js"
+    }
+  ],
+  "dependencies": [
+    {
+      "uuid": "c6193eda-f160-475b-ab65-fca17741e41b",
+      "version": [1, 0, 0]
+    },
+    {
+      "module_name": "@minecraft/server",
+      "version": "1.17.0"
+    }
+  ]
+}