feat(01-01): implement TypeScript interfaces and IndexedDB wrapper

- All shared interfaces: Progress, Settings, ForestElement, CompanionAssets, etc.
- IndexedDB wrapper with 5 stores (progress, companionAssets, styleReference, forestElements, settings)
- CRUD for progress and settings stores
- 5 passing tests with fake-indexeddb

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

package-lock.json

@@ -9,6 +9,7 @@
 			"version": "0.0.1",
 			"devDependencies": {
 				"@biomejs/biome": "^1.9.0",
+				"fake-indexeddb": "^6.2.5",
 				"typescript": "~5.8.0",
 				"vite": "^6.0.0",
 				"vitest": "^3.0.0"
@@ -1261,6 +1262,16 @@
 				"node": ">=12.0.0"
 			}
 		},
+		"node_modules/fake-indexeddb": {
+			"version": "6.2.5",
+			"resolved": "https://registry.npmjs.org/fake-indexeddb/-/fake-indexeddb-6.2.5.tgz",
+			"integrity": "sha512-CGnyrvbhPlWYMngksqrSSUT1BAVP49dZocrHuK0SvtR0D5TMs5wP0o3j7jexDJW01KSadjBp1M/71o/KR3nD1w==",
+			"dev": true,
+			"license": "Apache-2.0",
+			"engines": {
+				"node": ">=18"
+			}
+		},
 		"node_modules/fdir": {
 			"version": "6.5.0",
 			"resolved": "https://registry.npmjs.org/fdir/-/fdir-6.5.0.tgz",