docs: switch install instructions from SFTP to git clone, add update section

README.md

@@ -29,25 +29,40 @@ build off a Pi anyway.
 
 ## Installing on the Pi
 
-1. Copy the project folder onto the Pi however you like (SFTP, `scp -r`,
-   whatever) -- anywhere, the installer figures out its own location.
-2. On the Pi:
 ```bash
+git clone https://gitea.honeyy.duckdns.org/Honey/Paperwall.git /root/paperwall
+cd /root/paperwall
 sudo bash install.sh
 ```
 
 That's the whole thing. It installs the few system packages needed to build
-`lgpio` (`liblgpio-dev`, `swig`), enables SPI/I2C in `config.txt` if not
+`lgpio`/`spidev` (`liblgpio-dev`, `swig`, `python3-dev`), enables SPI/I2C in
-already on, creates its own venv right next to the project and installs
+`config.txt` if not already on, creates its own venv right next to the
-everything into it (`requirements.txt` + `requirements-pi.txt`), and
+project and installs everything into it (`requirements.txt` +
-installs+starts `paperwall.service`. If it finds InkyPi (or anything else)
+`requirements-pi.txt`), and installs+starts `paperwall.service`. If it finds
-already running, it stops it first -- two things can't drive the same panel
+InkyPi (or anything else) already running, it stops it first -- two things
-at once -- but nothing is copied from or reused out of it. Safe to re-run.
+can't drive the same panel at once -- but nothing is copied from or reused
+out of it. Safe to re-run.
 
 Then open `http://<pi-ip>:8080`, fill in Navidrome credentials under
 **Navidrome** and coordinates under **Weather**. Everything saves
 immediately and takes effect within a few seconds -- no restart needed.
 
+## Updating
+
+```bash
+cd /root/paperwall
+git pull
+sudo systemctl restart paperwall.service
+```
+
+`venv/` and `config.json` are gitignored, so `git pull` never touches your
+installed dependencies or your Navidrome/weather settings -- just the code.
+A plain restart is enough for most changes. Only re-run `sudo bash
+install.sh` when `requirements.txt` or `requirements-pi.txt` changed (new
+dependency) or you need SPI/I2C re-checked -- it's idempotent, safe to run
+any time.
+
 ## Uninstalling
 
 ```bash