feat: add Technitium DNS Home Assistant add-on

- repository.yaml manifest for HA add-on store
- technitium_dns add-on using upstream technitium/dns-server image
- config.yaml with ports 53/udp, 53/tcp, 5380/tcp and password schema
- Dockerfile symlinks /etc/dns to /data/dns for persistent config
- READMEs for repo and add-on

README.md

@@ -0,0 +1,42 @@
+# Hassio_Addons
+
+Home Assistant add-on repository hosting the Technitium DNS add-on.
+
+## Add-ons
+
+| Add-on | Description |
+|---|---|
+| [technitium_dns](./technitium_dns/) | Technitium DNS Server — local DNS with ad-blocking, web console, acts as secondary to a primary Technitium instance in Kubernetes via DNS Replication |
+
+## Add this repository to Home Assistant
+
+**Settings → Add-ons → Add-on Store → ⋮ (top right) → Repositories**
+
+```
+https://git.kenschiano.net/kschiano/Hassio_Addons.git
+```
+
+Then refresh the add-on store and install **Technitium DNS**.
+
+## Repo layout
+
+```
+Hassio_Addons/
+├── repository.yaml              # repository manifest (read by HA)
+└── technitium_dns/
+    ├── config.yaml               # add-on metadata, ports, schema
+    ├── Dockerfile               # thin layer on technitium/dns-server:latest
+    └── README.md
+```
+
+## Update workflow
+
+1. Bump `version` in `technitium_dns/config.yaml`.
+2. Commit and push to `git.kenschiano.net/kschiano/Hassio_Addons.git`.
+3. In Home Assistant: refresh the add-on store, update the add-on, rebuild.
+
+## Notes
+
+- The add-on uses the upstream `technitium/dns-server` image directly — no custom build pipeline needed.
+- Config persists to the add-on config volume (`/data/dns` symlinked to `/etc/dns`).
+- For primary/secondary replication setup, see `technitium_dns/README.md`.