Add history-ui workspace and supporting server endpoints

Splits history-ui out of asch/fix-everything into its own branch off
main. Includes the Svelte workspace, the three dedicated server
endpoints (list_vaults, fetch_vault_history, fetch_document_versions),
SPA asset embedding via rust-embed, and the matching TS mirror types in
sync-client.

Note: this branch will not compile against main on its own — the new
endpoints depend on database/error/config additions that live on
asch/fix-everything. Intended to be merged once asch/fix-everything
lands.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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"]
+}