feat: build and publish release images from version tags

Tagging v* builds both images on Gitea Actions and pushes them to the instance
registry, then smoke-tests the published stack. The frontend read its backend
URL through import.meta.env, which Vite resolves at build time, so an image
could only point at whatever the build host had; it now reads it at runtime.

README.md

@@ -26,12 +26,18 @@ eBook library management application.
 
 ### Installation (Production Deployment)
 
-1.  Clone the repository: `git clone <repository_url>` (Replace `<repository_url>` with the actual URL)
+1.  Clone the repository: `git clone https://git.jaroszew.ski/patrick/chitai.git`
 2.  Navigate to the project root: `cd chitai`
-3.  Build the Docker images: `docker compose build`
-4.  Copy the example environment file and configure: `cp .env.prod-example .env`
-5.  Run the Docker containers in detached mode: `docker compose up -d`
-6.  Access the frontend at: `http://localhost:3000/`
+3.  Copy the example environment file: `cp .env.prod-example .env`
+4.  Edit `.env`. At minimum set `CHITAI_TOKEN_SECRET` to something random, and set
+    `CHITAI_ORIGIN` to the URL you will reach the app on — logging in fails with a 403 if it
+    does not match. Pin `CHITAI_VERSION` to a release tag if you would rather not track `latest`.
+5.  Pull the released images: `docker compose pull`
+6.  Run the Docker containers in detached mode: `docker compose up -d`
+7.  Access the frontend at: `http://localhost:3000/`
+
+To build the images from source instead of pulling them, run `docker compose build` in place of
+step 5.
 
 ## Development