Add cups app (LinuxServer CUPS with full filter stack)

Mounts ./ppds into /usr/share/cups/model/custom so custom PPDs appear
as available drivers without any restart.  State persisted under
../../lib/cups.  Exposes cups-net for other containers to join and
print via IPP.

Made-with: Cursor

Author: romkey

apps/cups/.env.example

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+# UID/GID the CUPS process runs as inside the container.
+# Match the host user that owns ../../lib/cups if you care about file permissions.
+PUID=1000
+PGID=1000
+
+TZ=America/Los_Angeles
+
+#IMAGE_VERSION=latest

apps/cups/.rsync-exclude

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+# cups
+
+Containerised CUPS print server using the
+[LinuxServer CUPS image](https://docs.linuxserver.io/images/docker-cups/),
+which ships with a comprehensive set of print filters and supporting programs:
+
+| Package | Purpose |
+|---|---|
+| `cups` | Core print server and IPP listener |
+| `cups-filters` | PDF, PostScript, raster, and text filter chain |
+| `ghostscript` | PS/PDF rendering |
+| `poppler-utils` | PDF inspection and conversion |
+| `qpdf` | PDF linearisation and repair |
+| `imagemagick` | Image format conversion (PNG, JPEG, TIFF, …) |
+| `foomatic-db` + `foomatic-db-engine` | Generic printer driver database |
+| `printer-driver-gutenprint` | High-quality open-source raster drivers |
+| `hplip` | HP printer drivers |
+| `libcupsimage2t64` | CUPS raster image library |
+
+## Networks
+
+| Network alias | Actual network | Purpose |
+|---|---|---|
+| `cups` | `cups-net` | Other containers join this to submit print jobs |
+| `proxy` | `nginx-proxy-net` | Reverse proxy access to the CUPS web UI |
+
+## Volumes
+
+| Mount | Purpose |
+|---|---|
+| `../../lib/cups` → `/config` | All CUPS state: config, spool, logs, per-queue PPDs |
+| `./ppds` → `/usr/share/cups/model/custom` (read-only) | Custom PPD files; any PPD placed here appears as an available driver in the CUPS add-printer wizard |
+
+## Adding custom PPDs
+
+Drop `.ppd` files into the `ppds/` directory next to this file.  They are
+mounted read-only into CUPS's model directory and appear automatically under
+**Administration → Add Printer → Choose Driver** the next time you open the
+wizard (no restart required).
+
+Example — adding the Rongta RP326 driver:
+
+```sh
+cp /path/to/Printer80.ppd apps/cups/ppds/
+```
+
+## First-time setup
+
+```sh
+cp .env.example .env
+# Edit .env if you need non-default PUID/PGID or TZ
+docker compose up -d
+```
+
+The CUPS web UI is available at `http://cups:631` from other containers on
+`cups-net`, or via nginx-proxy-manager if you set up a proxy host pointing
+to `cups:631`.
+
+To allow other containers to print without credentials, open the CUPS web UI
+and under **Administration → Server** enable:
+
+- Allow printing from the Internet
+- Allow remote administration
+
+## Adding a printer from another container
+
+Any container that needs to print should join `cups-net`:
+
+```yaml
+networks:
+  cups:
+    external: true
+    name: cups-net
+```
+
+Then configure the app's printer URL as `ipp://cups:631/printers/<queue-name>`.
+
+## Stopping safely
+
+```sh
+docker compose down
+```

apps/cups/README.md

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+services:
+  cups:
+    image: lscr.io/linuxserver/cups:${IMAGE_VERSION:-latest}
+    container_name: cups
+    hostname: cups
+    restart: unless-stopped
+    environment:
+      PUID: ${PUID:-1000}
+      PGID: ${PGID:-1000}
+      TZ: ${TZ:-America/Los_Angeles}
+    volumes:
+      - ../../lib/cups:/config
+      - ./ppds:/usr/share/cups/model/custom:ro
+#   ports:
+#     - 631:631
+    networks:
+      - cups
+      - proxy
+    healthcheck:
+      test: ["CMD-SHELL", "curl -fSs http://localhost:631/ || exit 1"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 15s
+
+networks:
+  cups:
+    name: cups-net
+  proxy:
+    external: true
+    name: nginx-proxy-net