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/renderer/terminal/terminal-small.js

@@ -0,0 +1,85 @@
+const backgroundWhite = '\x1b[47m'
+const backgroundBlack = '\x1b[40m'
+const foregroundWhite = '\x1b[37m'
+const foregroundBlack = '\x1b[30m'
+const reset = '\x1b[0m'
+const lineSetupNormal = backgroundWhite + foregroundBlack // setup colors
+const lineSetupInverse = backgroundBlack + foregroundWhite // setup colors
+
+const createPalette = function (lineSetup, foregroundWhite, foregroundBlack) {
+  return {
+    // 1 ... white, 2 ... black, 0 ... transparent (default)
+
+    '00': reset + ' ' + lineSetup,
+    '01': reset + foregroundWhite + '▄' + lineSetup,
+    '02': reset + foregroundBlack + '▄' + lineSetup,
+    10: reset + foregroundWhite + '▀' + lineSetup,
+    11: ' ',
+    12: '▄',
+    20: reset + foregroundBlack + '▀' + lineSetup,
+    21: '▀',
+    22: '█'
+  }
+}
+
+/**
+ * Returns code for QR pixel
+ * @param {boolean[][]} modules
+ * @param {number} size
+ * @param {number} x
+ * @param {number} y
+ * @return {'0' | '1' | '2'}
+ */
+const mkCodePixel = function (modules, size, x, y) {
+  const sizePlus = size + 1
+  if ((x >= sizePlus) || (y >= sizePlus) || (y < -1) || (x < -1)) return '0'
+  if ((x >= size) || (y >= size) || (y < 0) || (x < 0)) return '1'
+  const idx = (y * size) + x
+  return modules[idx] ? '2' : '1'
+}
+
+/**
+ * Returns code for four QR pixels. Suitable as key in palette.
+ * @param {boolean[][]} modules
+ * @param {number} size
+ * @param {number} x
+ * @param {number} y
+ * @return {keyof palette}
+ */
+const mkCode = function (modules, size, x, y) {
+  return (
+    mkCodePixel(modules, size, x, y) +
+    mkCodePixel(modules, size, x, y + 1)
+  )
+}
+
+exports.render = function (qrData, options, cb) {
+  const size = qrData.modules.size
+  const data = qrData.modules.data
+
+  const inverse = !!(options && options.inverse)
+  const lineSetup = options && options.inverse ? lineSetupInverse : lineSetupNormal
+  const white = inverse ? foregroundBlack : foregroundWhite
+  const black = inverse ? foregroundWhite : foregroundBlack
+
+  const palette = createPalette(lineSetup, white, black)
+  const newLine = reset + '\n' + lineSetup
+
+  let output = lineSetup // setup colors
+
+  for (let y = -1; y < size + 1; y += 2) {
+    for (let x = -1; x < size; x++) {
+      output += palette[mkCode(data, size, x, y)]
+    }
+
+    output += palette[mkCode(data, size, size, y)] + newLine
+  }
+
+  output += reset
+
+  if (typeof cb === 'function') {
+    cb(null, output)
+  }
+
+  return output
+}