Rebrand CommGate to gsmnode and adopt new design system

Rename the whole project from CommGate to gsmnode and re-skin every
surface onto the new signal-green + ink design system (Space Grotesk /
IBM Plex Sans / JetBrains Mono, flat surfaces, two-arrow routing mark,
lowercase gsm+node wordmark).

- Web App + API panel: rewrite token layer, gn-* utilities, data-gsm-theme,
  new logo/favicon assets; both builds verified.
- Phone App (Flutter): green theme, new mark/wordmark widgets, adaptive
  launcher icons; rename Android applicationId/package to app.gsmnode.phone;
  bump AGP to 8.6.0 and google_fonts to 8.1.0; debug APK build verified.
- API Server (Go): panel routes, User-Agent, health service id, branding.
- Home Assistant Plugin: rename integration domain sms_gateway to gsmnode
  (folder, DOMAIN, services, entity ids, classes); py_compile verified.
- Update all READMEs; add .gitignore (excludes Design/, build artifacts).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Web App/server/Run-WebApp.ps1

@@ -0,0 +1,29 @@
+# Builds the Vue frontend (if needed) and runs the Web App BFF.
+#
+#   ./Run-WebApp.ps1            # build frontend then serve
+#   ./Run-WebApp.ps1 -SkipBuild # serve existing dist only
+
+param([switch]$SkipBuild)
+
+$ErrorActionPreference = "Stop"
+$serverDir = Split-Path -Parent $MyInvocation.MyCommand.Path
+$root = Split-Path -Parent $serverDir   # the "Web App" folder
+$webDir = Join-Path $root "web"
+
+$goBin = "C:\Program Files\Go\bin"
+if (Test-Path $goBin) { $env:Path = "$goBin;$env:Path" }
+
+if (-not $SkipBuild) {
+    Write-Host "Building frontend..." -ForegroundColor Cyan
+    Push-Location $webDir
+    try {
+        if (-not (Test-Path "node_modules")) { npm install }
+        npm run build
+    } finally { Pop-Location }
+}
+
+Push-Location $serverDir
+try {
+    Write-Host "Starting Web App on :8090 (Ctrl+C to stop)..." -ForegroundColor Cyan
+    go run .
+} finally { Pop-Location }