chore: bump version to v0.104.0 and refresh UI screenshots

Update v0.103.0 -> v0.104.0 across installer scripts, walkthrough docs,
and example go.mod files, and refresh the devices/migration/settings/sync
UI screenshots.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/content/docs/guides/EXTERNAL-HOST-WALKTHROUGH.md

@@ -40,7 +40,7 @@ starts on boot.
 To install a specific version:
 
 ```bash
-sudo bash install.sh v0.103.0
+sudo bash install.sh v0.104.0
 ```
 
 Check that the service is running:
@@ -263,7 +263,7 @@ curl -s http://192.0.2.1:8090/presets
 
 ```bash
 sudo bash install.sh              # updates to latest release
-sudo bash install.sh v0.103.0     # updates to a specific version
+sudo bash install.sh v0.104.0     # updates to a specific version
 ```
 
 The installer stops the service, downloads the new binary, and restarts

docs/content/docs/guides/ON-DEVICE-INSTALL-WALKTHROUGH.md

@@ -85,10 +85,10 @@ To target a specific version instead of the default:
 
 ```bash
 # Via environment variable (works with pipe-to-sh)
-VERSION=0.103.0 rw && curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh
+VERSION=0.104.0 rw && curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh
 
 # Via command-line flag (pass args after sh -s --)
-curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh -s -- --version 0.103.0
+curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh -s -- --version 0.104.0
 ```
 
 Verify the installed version:
@@ -97,7 +97,7 @@ Verify the installed version:
 wget -qO- http://localhost:8000/health
 ```
 
-The JSON response should include `"version":"v0.103.0"` (or whichever
+The JSON response should include `"version":"v0.104.0"` (or whichever
 version you installed).
 
 ---
@@ -185,13 +185,13 @@ next reboot — which is fine for a one-time setup run):
 cd /tmp
 
 curl -L --fail -o soundtouch-cli \
-  https://github.com/gesellix/Bose-SoundTouch/releases/download/v0.103.0/soundtouch-cli-v0.103.0-linux-armv7
+  https://github.com/gesellix/Bose-SoundTouch/releases/download/v0.104.0/soundtouch-cli-v0.104.0-linux-armv7
 chmod +x soundtouch-cli
 
 /tmp/soundtouch-cli --version
 ```
 
-Replace `v0.103.0` with the version you installed.
+Replace `v0.104.0` with the version you installed.
 
 ---
 
@@ -304,12 +304,12 @@ older artefacts to keep `/mnt/nv` free:
 rw && curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh
 
 # Update to a specific version — three equivalent forms
-VERSION=0.103.0 rw && curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh
+VERSION=0.104.0 rw && curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh
 
-rw && curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh -s -- --version 0.103.0
+rw && curl -sSL https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh | sh -s -- --version 0.104.0
 
 curl -sSLo install.sh https://raw.githubusercontent.com/gesellix/Bose-SoundTouch/main/scripts/on-device-install/install.sh
-sh install.sh --version 0.103.0
+sh install.sh --version 0.104.0
 ```
 
 **Rollback:** the installer keeps a `.backup` file alongside the binary:

docs/content/docs/guides/RASPBERRY-PI.md

@@ -34,14 +34,14 @@ sudo bash install.sh
 Install a specific version:
 
 ```bash
-sudo bash install.sh v0.103.0
+sudo bash install.sh v0.104.0
 ```
 
 Override defaults at install time:
 
 ```bash
 sudo \
-  VERSION=v0.103.0 \
+  VERSION=v0.104.0 \
   HOSTNAME_FQDN=soundtouch.local \
   HTTP_PORT=80 \
   HTTPS_PORT=443 \
@@ -99,7 +99,7 @@ journalctl -u soundtouch-service -b               # this boot only
 
 ```bash
 sudo bash install.sh              # update to latest release
-sudo bash install.sh v0.103.0     # update to a specific version
+sudo bash install.sh v0.104.0     # update to a specific version
 ```
 
 The script stops the service, downloads the new binary (backs up the old one to
@@ -134,14 +134,14 @@ sudo bash install-web.sh
 Install a specific version:
 
 ```bash
-sudo bash install-web.sh v0.103.0
+sudo bash install-web.sh v0.104.0
 ```
 
 Override defaults at install time:
 
 ```bash
 sudo \
-  VERSION=v0.103.0 \
+  VERSION=v0.104.0 \
   HTTP_PORT=8081 \
   bash install-web.sh
 ```
@@ -211,7 +211,7 @@ journalctl -u soundtouch-web -f
 
 ```bash
 sudo bash install-web.sh              # update to latest release
-sudo bash install-web.sh v0.103.0     # update to a specific version
+sudo bash install-web.sh v0.104.0     # update to a specific version
 ```
 
 ### Removal