GDPR compliance: self-host all assets, add Impressum + Datenschutz

- Self-host Tailwind, Plotly, D3.js (no more CDN requests)
- Self-host Inter font (no more Google Fonts requests)
- Replace JetBrains Mono with system monospace font stack
- Zero external requests when visiting the site (GDPR-safe)
- Add /impressum page (§5 TMG, §18 MStV)
- Add /datenschutz page (DSGVO Art. 13/14)
- Hosting: Hetzner, no cookies, no tracking, no analytics
- Add Impressum/Datenschutz links to sidebar footer
- Configure Flask static_folder for local asset serving

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/webui/app.py

@@ -44,6 +44,8 @@ from webui.data import (
 app = Flask(
     __name__,
     template_folder=str(Path(__file__).parent / "templates"),
+    static_folder=str(Path(__file__).parent / "static"),
+    static_url_path="/static",
 )
 app.config["SECRET_KEY"] = "ietf-dashboard-dev"
 
@@ -282,6 +284,16 @@ def about():
     return render_template("about.html", stats=stats)
 
 
+@app.route("/impressum")
+def impressum():
+    return render_template("impressum.html")
+
+
+@app.route("/datenschutz")
+def datenschutz():
+    return render_template("datenschutz.html")
+
+
 # --- API endpoints for AJAX (used by client-side charts) ---