split: history-ui (new Svelte workspace)

New web UI for browsing vault history. Svelte + Vite app with components
for activity feed, dashboard, document detail, diff view, file tree,
header, login, time slider, toast container, vault picker; lib/api.ts and
stores.svelte.ts for client state. (Generated TS types were added in
PR6.)

frontend/history-ui/tsconfig.json

@@ -0,0 +1,16 @@
+{
+    "compilerOptions": {
+        "target": "ESNext",
+        "module": "ESNext",
+        "moduleResolution": "bundler",
+        "strict": true,
+        "esModuleInterop": true,
+        "skipLibCheck": true,
+        "forceConsistentCasingInFileNames": true,
+        "resolveJsonModule": true,
+        "isolatedModules": true,
+        "verbatimModuleSyntax": true,
+        "types": ["svelte"]
+    },
+    "include": ["src/**/*", "src/**/*.svelte"]
+}