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>

.claude/launch.json

@@ -0,0 +1,19 @@
+{
+  "version": "0.0.1",
+  "configurations": [
+    {
+      "name": "web-app",
+      "runtimeExecutable": "npm",
+      "runtimeArgs": ["run", "dev"],
+      "cwd": "Web App/web",
+      "port": 5173
+    },
+    {
+      "name": "api-server",
+      "runtimeExecutable": "./api-server.exe",
+      "runtimeArgs": [],
+      "cwd": "API Server",
+      "port": 8080
+    }
+  ]
+}