Restructure frontend code to allow for extensions (#4721)

# Description of Changes
Move frontend code into `core` folder and add infrastructure for
`proprietary` folder to include premium, non-OSS features

frontend/package-lock.json

@@ -94,6 +94,7 @@
         "typescript": "^5.9.2",
         "typescript-eslint": "^8.44.1",
         "vite": "^7.1.7",
+        "vite-tsconfig-paths": "^5.1.4",
         "vitest": "^3.2.4"
       }
     },
@@ -7977,6 +7978,13 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
+    "node_modules/globrex": {
+      "version": "0.1.2",
+      "resolved": "https://registry.npmjs.org/globrex/-/globrex-0.1.2.tgz",
+      "integrity": "sha512-uHJgbwAMwNFf5mLst7IWLNg14x1CkeqglJb/K3doi4dw6q2IvAAmM/Y81kevy83wP+Sst+nutFTYOGg3d1lsxg==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/gonzales-pe": {
       "version": "4.3.0",
       "resolved": "https://registry.npmjs.org/gonzales-pe/-/gonzales-pe-4.3.0.tgz",
@@ -13298,6 +13306,27 @@
         "node": ">=18"
       }
     },
+    "node_modules/tsconfck": {
+      "version": "3.1.6",
+      "resolved": "https://registry.npmjs.org/tsconfck/-/tsconfck-3.1.6.tgz",
+      "integrity": "sha512-ks6Vjr/jEw0P1gmOVwutM3B7fWxoWBL2KRDb1JfqGVawBmO5UsvmWOQFGHBPl5yxYz4eERr19E6L7NMv+Fej4w==",
+      "dev": true,
+      "license": "MIT",
+      "bin": {
+        "tsconfck": "bin/tsconfck.js"
+      },
+      "engines": {
+        "node": "^18 || >=20"
+      },
+      "peerDependencies": {
+        "typescript": "^5.0.0"
+      },
+      "peerDependenciesMeta": {
+        "typescript": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/tsconfig-paths": {
       "version": "4.2.0",
       "resolved": "https://registry.npmjs.org/tsconfig-paths/-/tsconfig-paths-4.2.0.tgz",
@@ -13828,6 +13857,26 @@
         "url": "https://opencollective.com/vitest"
       }
     },
+    "node_modules/vite-tsconfig-paths": {
+      "version": "5.1.4",
+      "resolved": "https://registry.npmjs.org/vite-tsconfig-paths/-/vite-tsconfig-paths-5.1.4.tgz",
+      "integrity": "sha512-cYj0LRuLV2c2sMqhqhGpaO3LretdtMn/BVX4cPLanIZuwwrkVl+lK84E/miEXkCHWXuq65rhNN4rXsBcOB3S4w==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "debug": "^4.1.1",
+        "globrex": "^0.1.2",
+        "tsconfck": "^3.0.3"
+      },
+      "peerDependencies": {
+        "vite": "*"
+      },
+      "peerDependenciesMeta": {
+        "vite": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/vite/node_modules/fdir": {
       "version": "6.5.0",
       "resolved": "https://registry.npmjs.org/fdir/-/fdir-6.5.0.tgz",