feat: Add LocalSend (#35)

## Summary

This PR adds a section about https://localsend.org/

## Type of change

<!-- Check all that apply -->

- [x] `feat` — new page or feature

> [PR title and commit types must follow these standards — view the
contributing
guide](https://github.com/Stensel8/Zephyrus-Linux/blob/main/CONTRIBUTING.md#commit-messages)

## Checklist

- [x] PR title follows the commit convention (e.g. `fix: correct nmcli
command in eduroam guide`)
- [x] Both EN and NL versions updated (if applicable)
- [x] Media is in AVIF format (not PNG/JPG)
- [x] No broken image references (`/images/*.avif` all exist in
`static/images/`)
- [x] Tested locally with `hugo server`

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: Stensel8

content/docs/applications.md

@@ -499,3 +499,50 @@ sudo pacman -S solaar
 Runs in the system tray with battery notifications. You can also configure DPI, polling rate, and buttons from there.
 
 ![Solaar about screen - version 1.1.19](/images/solaar-about.avif)
+
+### LocalSend
+
+[LocalSend](https://localsend.org/) is an open-source, cross-platform file sharing app. I use it to transfer files between my Samsung S24 Ultra and the Zephyrus. If you're coming from Windows or Android, it's essentially the open-source equivalent of Quick Share: it discovers devices on the local network and transfers files directly, no cloud involved.
+
+The one thing it can't do is transfer files across different networks. Quick Share could route transfers through Google/Samsung's cloud when sender and receiver were on separate networks, but that was mobile-only. Desktop Quick Share was unreliable enough that it was rarely worth using anyway. Speed-wise, LocalSend is slightly slower, but not noticeably so in practice.
+
+Available natively in the [CachyOS package repository](https://packages.cachyos.org/package/cachyos/x86_64/localsend), built specifically for CachyOS. No AUR needed, which is a real plus.
+
+```bash
+sudo pacman -S localsend
+```
+
+The app shows up in the GNOME launcher after installing. Open it and it auto-discovers other LocalSend instances on your network.
+
+<img src="/images/localsend-desktop.avif" width="700" alt="LocalSend running on the desktop">
+
+<img src="/images/localsend-cachyos-package.avif" width="600" alt="LocalSend in the CachyOS package repository">
+
+**Firewall rules**
+
+LocalSend uses port 53317 (TCP and UDP) for both device discovery and file transfer. If you have a firewall active, you need to open this port.
+
+**ufw:**
+
+```bash
+sudo ufw allow 53317/tcp comment "LocalSend-App"
+sudo ufw allow 53317/udp comment "LocalSend-App"
+```
+
+**firewalld:**
+
+```bash
+sudo firewall-cmd --permanent --add-port=53317/tcp
+sudo firewall-cmd --permanent --add-port=53317/udp
+sudo firewall-cmd --reload
+```
+
+The Android app works the same way. Open it on your phone and it immediately appears as a discovered device on the desktop side, and vice versa.
+
+<img src="/images/localsend-android-1.avif" width="320" alt="LocalSend on Android (Samsung S24 Ultra)">
+
+Selecting files is straightforward. Pick what you want to send, choose the target device, and the transfer starts.
+
+<img src="/images/localsend-android-2.avif" width="320" alt="LocalSend on Android - selecting files to send">
+
+<img src="/images/localsend-android-3.avif" width="320" alt="LocalSend on Android - transfer in progress">

content/docs/applications.nl.md

@@ -499,3 +499,50 @@ sudo pacman -S solaar
 Draait in het systray met batterijnotificaties. Je kunt er ook DPI, polling rate en knoppen mee configureren.
 
 ![Solaar about screen - version 1.1.19](/images/solaar-about.avif)
+
+### LocalSend
+
+[LocalSend](https://localsend.org/) is een open-source, platformonafhankelijke app voor het delen van bestanden. Ik gebruik het om bestanden over te zetten tussen mijn Samsung S24 Ultra en de Zephyrus. Als je gewend bent aan Windows of Android, is het in feite het open-source equivalent van QuickShare: het ontdekt apparaten op het lokale netwerk en stuurt bestanden direct door, zonder cloud.
+
+Wat het niet kan, is bestanden versturen wanneer afzender en ontvanger op verschillende netwerken zitten. QuickShare kon dat wel via de cloud van Google en Samsung, maar dat was toch alleen beschikbaar via de mobiele app. De desktopversie van QuickShare werkte sowieso niet altijd even goed, dus in de praktijk mis je dat niet. Qua snelheid is LocalSend iets langzamer, maar dat merk je nauwelijks.
+
+Beschikbaar als native pakket in de [CachyOS-packagerepository](https://packages.cachyos.org/package/cachyos/x86_64/localsend), native gebouwd voor CachyOS. Geen AUR nodig, wat echt een pluspunt is.
+
+```bash
+sudo pacman -S localsend
+```
+
+Na het installeren verschijnt de app in de GNOME-launcher. Open hem en hij ontdekt direct andere LocalSend-instanties op het netwerk.
+
+<img src="/images/localsend-desktop.avif" width="700" alt="LocalSend draaiend op de desktop">
+
+<img src="/images/localsend-cachyos-package.avif" width="600" alt="LocalSend in de CachyOS-packagerepository">
+
+**Firewallregels**
+
+LocalSend gebruikt poort 53317 (TCP en UDP) voor zowel apparaatdetectie als bestandsoverdracht. Als je een firewall actief hebt, moet je deze poort openstellen.
+
+**ufw:**
+
+```bash
+sudo ufw allow 53317/tcp comment "LocalSend-App"
+sudo ufw allow 53317/udp comment "LocalSend-App"
+```
+
+**firewalld:**
+
+```bash
+sudo firewall-cmd --permanent --add-port=53317/tcp
+sudo firewall-cmd --permanent --add-port=53317/udp
+sudo firewall-cmd --reload
+```
+
+De Android-app werkt op dezelfde manier. Open hem op je telefoon en hij verschijnt meteen als ontdekt apparaat aan de desktopkant, en andersom.
+
+<img src="/images/localsend-android-1.avif" width="320" alt="LocalSend op Android (Samsung S24 Ultra)">
+
+Bestanden selecteren gaat eenvoudig. Kies wat je wilt versturen, selecteer het doelapparaat en de overdracht begint.
+
+<img src="/images/localsend-android-2.avif" width="320" alt="LocalSend op Android - bestanden selecteren">
+
+<img src="/images/localsend-android-3.avif" width="320" alt="LocalSend op Android - overdracht bezig">