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>

lobby-addon/lobby_transfer_RP/models/blocks/portal_field.geo.json

@@ -0,0 +1,25 @@
+{
+  "format_version": "1.12.0",
+  "minecraft:geometry": [
+    {
+      "description": {
+        "identifier": "geometry.silverlabs.portal_field",
+        "texture_width": 16,
+        "texture_height": 16,
+        "visible_bounds_width": 1.5,
+        "visible_bounds_height": 2,
+        "visible_bounds_offset": [0, 0.5, 0]
+      },
+      "bones": [
+        {
+          "name": "field",
+          "pivot": [0, 0, 0],
+          "cubes": [
+            { "origin": [-7, 0, -1], "size": [14, 16, 2], "uv": [0, 0] },
+            { "origin": [-1, 0, -7], "size": [2, 16, 14], "uv": [0, 0] }
+          ]
+        }
+      ]
+    }
+  ]
+}