chore: replace Unicode/emoji icons with Lucide React

Adds lucide-react and replaces all HTML entity and emoji icons across
the UI with proper SVG icon components. Tree-shaken — only imported
icons are bundled.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/package-lock.json

@@ -10,6 +10,7 @@
       "dependencies": {
         "@cameleer/design-system": "^0.1.17",
         "@tanstack/react-query": "^5.90.21",
+        "lucide-react": "^1.7.0",
         "openapi-fetch": "^0.17.0",
         "react": "^19.2.4",
         "react-dom": "^19.2.4",
@@ -2583,6 +2584,15 @@
         "yallist": "^3.0.2"
       }
     },
+    "node_modules/lucide-react": {
+      "version": "1.7.0",
+      "resolved": "https://registry.npmjs.org/lucide-react/-/lucide-react-1.7.0.tgz",
+      "integrity": "sha512-yI7BeItCLZJTXikmK4KNUGCKoGzSvbKlfCvw44bU4fXAL6v3gYS4uHD1jzsLkfwODYwI6Drw5Tu9Z5ulDe0TSg==",
+      "license": "ISC",
+      "peerDependencies": {
+        "react": "^16.5.1 || ^17.0.0 || ^18.0.0 || ^19.0.0"
+      }
+    },
     "node_modules/minimatch": {
       "version": "3.1.5",
       "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.5.tgz",