fix: validate detected release tag in install script version detection

When the GitHub request fails (unreachable network, rate limiting — common
on Proxmox homelab VMs with broken IPv6/DNS), curl -f fails but -w still
prints the attempted URL, so detect_version() returned
"https://github.com/dokploy/dokploy/releases/latest" instead of a tag.
The resulting invalid image (dokploy/dokploy:https://...) meant the dokploy
service was never created, traefik.yml was never written, and the bind
mount created it as a directory.

Accept only values that look like a release tag (v0.x.y), falling back to
"latest" otherwise, and add --connect-timeout 10 so blackholed networks
fail over in seconds instead of hanging the install.

Verified on debian:13 containers: normal network detects v0.29.10, the
DOKPLOY_VERSION override is intact, and connection-refused or blackholed
github.com now falls back to "latest" within 10s.

Fixes #126

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/website/public/install.sh

@@ -19,10 +19,19 @@ detect_version() {
         echo "Detecting latest stable version from GitHub..." >&2
         
         # Try to get latest release from GitHub by following redirects
-        version=$(curl -fsSL -o /dev/null -w '%{url_effective}\n' \
+        version=$(curl -fsSL --connect-timeout 10 -o /dev/null -w '%{url_effective}\n' \
             https://github.com/dokploy/dokploy/releases/latest 2>/dev/null | \
             sed 's#.*/tag/##')
-        
+
+        # When the request fails (unreachable network, rate limit), curl still
+        # prints the attempted URL, which would produce an invalid image tag
+        # like dokploy/dokploy:https://... Accept only values that look like a
+        # release tag (e.g. v0.29.10).
+        case "$version" in
+            v[0-9]*) ;;
+            *) version="" ;;
+        esac
+
         # Fallback to latest tag if detection fails
         if [ -z "$version" ]; then
             echo "Warning: Could not detect latest version from GitHub, using fallback version latest" >&2