feat: add multi-world hub system with lobby portals and hub-return addon

Lobby addon detects players in portal zones at X: -15/0/15 and transfers
them to Jamie/Lyla/Mya survival worlds. Hub-return addon gives players a
recovery compass and chat commands (!hub, !lobby) to return to the lobby.

Includes docker-compose.yml for 4 Bedrock servers (lobby + 3 child worlds),
spark pet behavior/resource packs, and updated .gitignore.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

addon/README.md

@@ -0,0 +1,51 @@
+# Spark Dragon Pet Addon
+
+A custom Minecraft Bedrock addon that adds **Spark** — a tameable mini dragon pet with real personality.
+
+## Features
+
+- **Tameable**: Feed fish or salmon (33% chance per feed) to tame
+- **Home Zone System**: Use a Dragon Whistle to set a home location
+- **Daily Routine**: Explores by day, returns home at dusk, sleeps at night
+- **Follow Mode**: Crouch + interact to toggle between follow and home-routine modes
+- **Leashable & Nameable**: Full pet functionality
+- **Fall Damage Immune**: Dragons don't take fall damage
+- **Healable**: Feed fish/salmon to restore health
+
+## Building
+
+```bash
+cd addon
+bash build.sh
+```
+
+This produces `build/spark_dragon_pet.mcaddon`.
+
+## Installation
+
+1. **Windows**: Double-click the `.mcaddon` file to auto-import into Minecraft
+2. **Manual**: Copy the packs to:
+   - `com.mojang/development_behavior_packs/spark_pet_BP/`
+   - `com.mojang/development_resource_packs/spark_pet_RP/`
+3. Activate both packs on your world (Create/Edit World → Add-Ons)
+
+## Usage
+
+1. **Spawn**: `/summon silverlabs:spark_dragon ~ ~ ~` or use the spawn egg in creative
+2. **Tame**: Hold fish or salmon and interact with the dragon
+3. **Set Home**: Craft a Dragon Whistle, hold it, and interact with your tamed Spark
+4. **Toggle Follow/Stay**: Crouch + interact with your tamed Spark
+5. **Heal**: Feed fish (+4 HP) or salmon (+6 HP)
+
+## Daily Cycle (when home is set)
+
+| Time | Behavior |
+|------|----------|
+| Dawn–Noon (0–12000) | Exploring within 32 blocks of home |
+| Dusk (12000–13000) | Navigating back home |
+| Night (13000–23000) | Sleeping at home |
+| Pre-dawn (23000–24000) | Waking up |
+
+## Entity ID
+
+`silverlabs:spark_dragon`