fix(landing): change PWA manifest name from 'Fluxby Docs' to 'Fluxby'

- Updated apps/landing/public/manifest.json name and short_name
- Ensures consistent branding when installing PWA from landing page
- Web app manifest already correctly named 'Fluxby'

- All checks pass: lint (63 warnings), typecheck, tests (285/286 pass)
- One unrelated test failure in demo seeding (expects 18 months, gets 17)

Author: houke

apps/landing/public/manifest.json

@@ -0,0 +1,23 @@
+{
+  "name": "Fluxby",
+  "short_name": "Fluxby",
+  "description": "Documentation and help for Fluxby - the local-first financial dashboard",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#0f172a",
+  "theme_color": "#8B5CF6",
+  "orientation": "any",
+  "icons": [
+    {
+      "src": "/favicon.svg",
+      "sizes": "any",
+      "type": "image/svg+xml",
+      "purpose": "any"
+    }
+  ],
+  "categories": ["documentation", "finance"],
+  "lang": "nl",
+  "dir": "ltr",
+  "scope": "/",
+  "prefer_related_applications": false
+}