feat(ui): Symbole fuer Tab, Startbildschirm und Manifest (#017)

npm run icons erzeugt SVG, ICO und PNG aus den Vorlagen in assets/. Fuer kleine
Groessen kommen die vereinfachten Fassungen zum Einsatz.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "proxledger",
-  "version": "0.9.0",
+  "version": "0.12.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "proxledger",
-      "version": "0.9.0",
+      "version": "0.12.0",
       "hasInstallScript": true,
       "dependencies": {
         "@node-rs/argon2": "^2.2.1",
@@ -37,6 +37,7 @@
         "eslint-config-prettier": "^10.1.8",
         "prettier": "^3.9.7",
         "prisma": "^7.10.0",
+        "sharp": "^0.35.4",
         "tsx": "^4.23.13",
         "typescript": "^5",
         "vitest": "^5.0.1"
@@ -1013,8 +1014,8 @@
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/@img/colour/-/colour-1.1.0.tgz",
       "integrity": "sha512-Td76q7j57o/tLVdgS746cYARfSyxk8iEfRxewL9h4OMzYhbW4TAcppl0mT4eyqXddh6L/jwoM75mo7ixa/pCeQ==",
+      "devOptional": true,
       "license": "MIT",
-      "optional": true,
       "engines": {
         "node": ">=18"
       }
@@ -9117,8 +9118,8 @@
       "version": "0.35.4",
       "resolved": "https://registry.npmjs.org/sharp/-/sharp-0.35.4.tgz",
       "integrity": "sha512-n++8XWcj+jCOr2IOl7h8LbKnGBDY4aPbmprMONBNFdn0ImXqpGVv5zliDs0V9HbmbCQLpbuo2ej9rAoOQTvMDA==",
+      "devOptional": true,
       "license": "Apache-2.0",
-      "optional": true,
       "dependencies": {
         "@img/colour": "^1.1.0",
         "detect-libc": "^2.1.2",
@@ -9167,8 +9168,8 @@
       "version": "7.8.5",
       "resolved": "https://registry.npmjs.org/semver/-/semver-7.8.5.tgz",
       "integrity": "sha512-Y7/KDsb8LjooZpwaqGyulO6DQlksgCncchHGk+sZIY4SBvUocMBEFH5Ur1fI4dV+Jvl0w6cjvucaIi40puRioA==",
+      "devOptional": true,
       "license": "ISC",
-      "optional": true,
       "bin": {
         "semver": "bin/semver.js"
       },