feat: Add docker_ignis for self-hosted Obsidian sync server

[haobibo]

Summary

This PR adds support for deploying a self-hosted Ignis server (Obsidian sync server) using Docker.

Changes

• ignis.Dockerfile: Multi-stage build based on labnow/node image, clones and builds ignis from source at https://github.com/Nystik-gh/ignis
• work/start-ignis.sh: Startup script for bootstrap and healthcheck
• demo/docker-compose.yml: Docker Compose configuration with port 8080 and volume mounts
• demo/.env.example: Example environment configuration
• README.md: Complete documentation for deployment and usage

Features

• Self-hosted Obsidian vault synchronization
• Port 8080 for web interface
• Automatic Obsidian download on first run
• Data persistence via volumes (/vaults, /app/data, /app/obsidian-app)
• Configurable user/group ownership via PUID/PGID

Usage

# Build image
source ./tool.sh
build_image_no_tag ignis local docker_ignis/ignis.Dockerfile

# Start with Docker Compose
cd docker_ignis/demo
docker compose up -d

References

• Ignis GitHub: https://github.com/Nystik-gh/ignis
• Official Docs: https://ignis.thiefling.com/docs/server/deploy/

@haobibo can click here to continue refining the PR

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