feat: app icon/splash asset guidelines + app.json config (FIBEROPS-209)

- Fix slug typo: "firberops" → "fiberops"
- Update splash backgroundColor to brand #F8FAFC (was Expo default #2563EB)
- Update android adaptiveIcon backgroundColor to brand cyan #0891B2
- Add assets/ASSETS.md with full brand guidelines (colors, fonts, dimensions)
- Add scripts/generate-assets.sh to regenerate PNGs from SVG sources via inkscape/rsvg-convert

app.json

@@ -1,7 +1,7 @@
 {
   "expo": {
     "name": "FiberOps",
-    "slug": "firberops",
+    "slug": "fiberops",
     "version": "1.0.0",
     "orientation": "portrait",
     "icon": "./assets/icon.png",
@@ -10,7 +10,7 @@
     "splash": {
       "image": "./assets/splash-icon.png",
       "resizeMode": "contain",
-      "backgroundColor": "#2563EB"
+      "backgroundColor": "#F8FAFC"
     },
     "ios": {
       "supportsTablet": false,
@@ -19,7 +19,7 @@
     "android": {
       "adaptiveIcon": {
         "foregroundImage": "./assets/adaptive-icon.png",
-        "backgroundColor": "#2563EB"
+        "backgroundColor": "#0891B2"
       },
       "package": "com.fiberops.mobile",
       "permissions": [