fix(docs): Swagger/ReDoc-Assets lokal statt von cdn.jsdelivr.net

/docs blieb leer wenn das CDN vom Client-Netzwerk aus nicht erreichbar
war (Firewall/Proxy) – Backend lieferte korrektes HTML, aber Swagger-UI-
JS/CSS und ReDoc-JS kamen nicht an. Jetzt unter app/static/swagger-ui/
gebündelt und über eigene /docs+/redoc-Routen ausgeliefert (nur Dev,
Production weiterhin ohne interaktive Docs).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015Ahyx6D3r7G1EuAc42nezn

backend/app/main.py

@@ -3,6 +3,8 @@ from contextlib import asynccontextmanager
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.middleware.trustedhost import TrustedHostMiddleware
+from fastapi.openapi.docs import get_redoc_html, get_swagger_ui_html
+from fastapi.staticfiles import StaticFiles
 from slowapi import _rate_limit_exceeded_handler
 from slowapi.errors import RateLimitExceeded
 
@@ -62,14 +64,39 @@ async def lifespan(app: FastAPI):
 app = FastAPI(
     title=settings.app_name,
     version="0.1.0",
-    docs_url="/docs" if not settings.is_production else None,
-    redoc_url="/redoc" if not settings.is_production else None,
+    docs_url=None,   # eigene Route unten – Swagger-Assets lokal statt CDN
+    redoc_url=None,  # eigene Route unten – ReDoc-Assets lokal statt CDN
     lifespan=lifespan,
 )
 
 app.state.limiter = limiter
 app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)
 
+# Swagger/ReDoc-Assets lokal ausliefern statt von cdn.jsdelivr.net – Netzwerke ohne
+# CDN-Zugriff (Firewall/Proxy) zeigten sonst eine leere /docs-Seite.
+if not settings.is_production:
+    app.mount("/static", StaticFiles(directory="app/static"), name="static")
+
+    @app.get("/docs", include_in_schema=False)
+    async def custom_swagger_ui_html():
+        return get_swagger_ui_html(
+            openapi_url=app.openapi_url,
+            title=f"{app.title} - Swagger UI",
+            swagger_js_url="/static/swagger-ui/swagger-ui-bundle.js",
+            swagger_css_url="/static/swagger-ui/swagger-ui.css",
+            swagger_favicon_url="/static/swagger-ui/favicon.png",
+        )
+
+    @app.get("/redoc", include_in_schema=False)
+    async def custom_redoc_html():
+        return get_redoc_html(
+            openapi_url=app.openapi_url,
+            title=f"{app.title} - ReDoc",
+            redoc_js_url="/static/swagger-ui/redoc.standalone.js",
+            redoc_favicon_url="/static/swagger-ui/favicon.png",
+            with_google_fonts=False,
+        )
+
 # ── Middleware ────────────────────────────────────────────────────────────────
 
 app.add_middleware(