feat: 3D blobber dungeon generator (PR 1)

Replaces the 2D-only demo pipeline with a 3D cell-based blobber
generator. Per-cell face walls, per-material mesh emission, and a
GDExtension binding that returns a Dictionary with ArrayMesh surfaces
the demo consumes directly.

- src/blobber/: cell3d_t data model, dungeon container, pipeline that
  wraps the 2D generator per level and materializes into cell3d
- src/mesh/: face-quad emitter with per-material groups + .obj dump
- src/genesis3d_main.c: new CLI driving the blobber + mesh
- godot/: BrogueGen.generate_dungeon(seed, num_levels, depth) binding
  with dungeon_to_dict packing cells + mesh surfaces
- demo/: demo_blobber.tscn + dungeon_builder.gd, func_godot addon for
  the .map export path, point/entity templates, TrenchBroom docs
- Retired: old arcade/FPS demo scenes and their scripts, unused meshlib

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

demo/addons/func_godot/game_config/trenchbroom/func_godot_tb_game_config.tres

@@ -0,0 +1,11 @@
+[gd_resource type="Resource" script_class="TrenchBroomGameConfig" format=3 uid="uid://b44ah5b2000wa"]
+
+[ext_resource type="Resource" uid="uid://crgpdahjaj" path="res://addons/func_godot/fgd/func_godot_fgd.tres" id="1_8u1vq"]
+[ext_resource type="Resource" uid="uid://b4xhdj0e16lop" path="res://addons/func_godot/game_config/trenchbroom/tb_face_tag_clip.tres" id="1_rsp20"]
+[ext_resource type="Resource" uid="uid://ca7377sfgj074" path="res://addons/func_godot/game_config/trenchbroom/tb_face_tag_skip.tres" id="2_166i2"]
+[ext_resource type="Script" uid="uid://cx44c4vnq8bt5" path="res://addons/func_godot/src/trenchbroom/trenchbroom_game_config.gd" id="2_ns6ah"]
+[ext_resource type="Resource" uid="uid://bkjxc54mmdhbo" path="res://addons/func_godot/game_config/trenchbroom/tb_face_tag_origin.tres" id="3_stisi"]
+[ext_resource type="Texture2D" uid="uid://decwujsyhj0qy" path="res://addons/func_godot/icon32.png" id="6_tex5j"]
+
+[resource]
+script = ExtResource("2_ns6ah")

demo/addons/func_godot/game_config/trenchbroom/tb_brush_tag_func.tres

@@ -0,0 +1,10 @@
+[gd_resource type="Resource" script_class="TrenchBroomTag" load_steps=2 format=3 uid="uid://37iduqf7tpxq"]
+
+[ext_resource type="Script" uid="uid://b66qdknwqpfup" path="res://addons/func_godot/src/trenchbroom/trenchbroom_tag.gd" id="1_rn13a"]
+
+[resource]
+script = ExtResource("1_rn13a")
+tag_name = "Func"
+tag_attributes = Array[String]([])
+tag_match_type = 1
+tag_pattern = "func*"

demo/addons/func_godot/game_config/trenchbroom/tb_brush_tag_trigger.tres

@@ -0,0 +1,10 @@
+[gd_resource type="Resource" script_class="TrenchBroomTag" load_steps=2 format=3 uid="uid://co2sb1ng7cw4i"]
+
+[ext_resource type="Script" uid="uid://b66qdknwqpfup" path="res://addons/func_godot/src/trenchbroom/trenchbroom_tag.gd" id="1_msqpk"]
+
+[resource]
+script = ExtResource("1_msqpk")
+tag_name = "Trigger"
+tag_match_type = 1
+tag_pattern = "trigger*"
+texture_name = "trigger"

demo/addons/func_godot/game_config/trenchbroom/tb_face_tag_clip.tres

@@ -0,0 +1,8 @@
+[gd_resource type="Resource" script_class="TrenchBroomTag" load_steps=2 format=3 uid="uid://b4xhdj0e16lop"]
+
+[ext_resource type="Script" uid="uid://b66qdknwqpfup" path="res://addons/func_godot/src/trenchbroom/trenchbroom_tag.gd" id="1_7td58"]
+
+[resource]
+script = ExtResource("1_7td58")
+tag_name = "Clip"
+tag_pattern = "clip"

demo/addons/func_godot/game_config/trenchbroom/tb_face_tag_origin.tres

@@ -0,0 +1,8 @@
+[gd_resource type="Resource" script_class="TrenchBroomTag" load_steps=2 format=3 uid="uid://bkjxc54mmdhbo"]
+
+[ext_resource type="Script" uid="uid://b66qdknwqpfup" path="res://addons/func_godot/src/trenchbroom/trenchbroom_tag.gd" id="1_enkfc"]
+
+[resource]
+script = ExtResource("1_enkfc")
+tag_name = "Origin"
+tag_pattern = "origin"

demo/addons/func_godot/game_config/trenchbroom/tb_face_tag_skip.tres

@@ -0,0 +1,8 @@
+[gd_resource type="Resource" script_class="TrenchBroomTag" load_steps=2 format=3 uid="uid://ca7377sfgj074"]
+
+[ext_resource type="Script" uid="uid://b66qdknwqpfup" path="res://addons/func_godot/src/trenchbroom/trenchbroom_tag.gd" id="1_2teqe"]
+
+[resource]
+script = ExtResource("1_2teqe")
+tag_name = "Skip"
+tag_pattern = "skip"