Scaffold kvida-sdk: Vite + TypeScript web client for device settings

First real content in this repo. Runs as a standalone web app (not on
the ESP32 -- Blockly is far too large for the device's flash),
talking to a device already on the LAN via the JSON API kvida-os now
exposes (see kvida-os's transport README, "JSON API" section).

One page: enter a device address, fetch /api/status + /api/mqtt,
edit and save MQTT broker/credentials back via POST /api/mqtt. Proves
the API end-to-end from a real standalone app before any Blockly work
starts.

No framework yet -- kept minimal until the Blockly editor itself is
designed. Verified: npm install/build are clean (no TS errors), and
the dev server was confirmed reachable with the device's CORS headers
allowing cross-origin fetch() calls from it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tsconfig.json

@@ -0,0 +1,18 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "useDefineForClassFields": true,
+    "module": "ESNext",
+    "lib": ["ES2022", "DOM", "DOM.Iterable"],
+    "skipLibCheck": true,
+    "moduleResolution": "bundler",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "noEmit": true,
+    "strict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noFallthroughCasesInSwitch": true
+  },
+  "include": ["src"]
+}