feat(security,ui): self-host React deps, Tailwind, fonts; strict CSP; local QR; better selection state

Replace CDN React/ReactDOM/Babel with local libs; remove Babel and inline scripts
Build Tailwind locally, add safelist; switch to assets/tailwind.css
Self-host Font Awesome and Inter (CSS + woff2); remove external font CDNs
Implement strict CSP (no unsafe-inline/eval; scripts/styles/fonts from self)
Extract inline handlers; move PWA scripts to external files
Add local QR code generation (qrcode lib) and remove api.qrserver.com
Improve SessionTypeSelector visual selection (highlighted background and ring)
Keep PWA working with service worker and offline assets
Refs: CSP hardening, offline-first, no external dependencies

node_modules/qrcode/lib/browser.js

@@ -0,0 +1,76 @@
+
+const canPromise = require('./can-promise')
+
+const QRCode = require('./core/qrcode')
+const CanvasRenderer = require('./renderer/canvas')
+const SvgRenderer = require('./renderer/svg-tag.js')
+
+function renderCanvas (renderFunc, canvas, text, opts, cb) {
+  const args = [].slice.call(arguments, 1)
+  const argsNum = args.length
+  const isLastArgCb = typeof args[argsNum - 1] === 'function'
+
+  if (!isLastArgCb && !canPromise()) {
+    throw new Error('Callback required as last argument')
+  }
+
+  if (isLastArgCb) {
+    if (argsNum < 2) {
+      throw new Error('Too few arguments provided')
+    }
+
+    if (argsNum === 2) {
+      cb = text
+      text = canvas
+      canvas = opts = undefined
+    } else if (argsNum === 3) {
+      if (canvas.getContext && typeof cb === 'undefined') {
+        cb = opts
+        opts = undefined
+      } else {
+        cb = opts
+        opts = text
+        text = canvas
+        canvas = undefined
+      }
+    }
+  } else {
+    if (argsNum < 1) {
+      throw new Error('Too few arguments provided')
+    }
+
+    if (argsNum === 1) {
+      text = canvas
+      canvas = opts = undefined
+    } else if (argsNum === 2 && !canvas.getContext) {
+      opts = text
+      text = canvas
+      canvas = undefined
+    }
+
+    return new Promise(function (resolve, reject) {
+      try {
+        const data = QRCode.create(text, opts)
+        resolve(renderFunc(data, canvas, opts))
+      } catch (e) {
+        reject(e)
+      }
+    })
+  }
+
+  try {
+    const data = QRCode.create(text, opts)
+    cb(null, renderFunc(data, canvas, opts))
+  } catch (e) {
+    cb(e)
+  }
+}
+
+exports.create = QRCode.create
+exports.toCanvas = renderCanvas.bind(null, CanvasRenderer.render)
+exports.toDataURL = renderCanvas.bind(null, CanvasRenderer.renderToDataURL)
+
+// only svg for now.
+exports.toString = renderCanvas.bind(null, function (data, _, opts) {
+  return SvgRenderer.render(data, opts)
+})