Add password-visibility toggle to login page (TypeScript)

- web/ts/login.ts: small vanilla TS module toggling the password input's
  type between 'password'/'text' via a 'Show/Hide' button, so users can
  rule out typos before submitting. Compiled to web/static/login.js
  (ES module) via tsc (web/tsconfig.json, new 'make web-ts'/'web-assets'
  Makefile targets) and loaded via <script type="module">. Compiled JS
  is committed/embedded the same way as the compiled CSS — no Node.js
  needed at runtime.
- Verified end-to-end against the live proxied server
  (https://local.unqr.dev/web/login): POST /web/login correctly returns
  303 + Set-Cookie, and the session then authorizes GET /web/ — the
  server-side login flow is confirmed working correctly.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

web/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "es2020",
+    "lib": ["ES2020", "DOM"],
+    "strict": true,
+    "noEmitOnError": true,
+    "rootDir": "./ts",
+    "outDir": "./static"
+  },
+  "include": ["ts/**/*.ts"]
+}