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/core/bit-matrix.js

@@ -0,0 +1,65 @@
+/**
+ * Helper class to handle QR Code symbol modules
+ *
+ * @param {Number} size Symbol size
+ */
+function BitMatrix (size) {
+  if (!size || size < 1) {
+    throw new Error('BitMatrix size must be defined and greater than 0')
+  }
+
+  this.size = size
+  this.data = new Uint8Array(size * size)
+  this.reservedBit = new Uint8Array(size * size)
+}
+
+/**
+ * Set bit value at specified location
+ * If reserved flag is set, this bit will be ignored during masking process
+ *
+ * @param {Number}  row
+ * @param {Number}  col
+ * @param {Boolean} value
+ * @param {Boolean} reserved
+ */
+BitMatrix.prototype.set = function (row, col, value, reserved) {
+  const index = row * this.size + col
+  this.data[index] = value
+  if (reserved) this.reservedBit[index] = true
+}
+
+/**
+ * Returns bit value at specified location
+ *
+ * @param  {Number}  row
+ * @param  {Number}  col
+ * @return {Boolean}
+ */
+BitMatrix.prototype.get = function (row, col) {
+  return this.data[row * this.size + col]
+}
+
+/**
+ * Applies xor operator at specified location
+ * (used during masking process)
+ *
+ * @param {Number}  row
+ * @param {Number}  col
+ * @param {Boolean} value
+ */
+BitMatrix.prototype.xor = function (row, col, value) {
+  this.data[row * this.size + col] ^= value
+}
+
+/**
+ * Check if bit at specified location is reserved
+ *
+ * @param {Number}   row
+ * @param {Number}   col
+ * @return {Boolean}
+ */
+BitMatrix.prototype.isReserved = function (row, col) {
+  return this.reservedBit[row * this.size + col]
+}
+
+module.exports = BitMatrix