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/kanji-data.js

@@ -0,0 +1,54 @@
+const Mode = require('./mode')
+const Utils = require('./utils')
+
+function KanjiData (data) {
+  this.mode = Mode.KANJI
+  this.data = data
+}
+
+KanjiData.getBitsLength = function getBitsLength (length) {
+  return length * 13
+}
+
+KanjiData.prototype.getLength = function getLength () {
+  return this.data.length
+}
+
+KanjiData.prototype.getBitsLength = function getBitsLength () {
+  return KanjiData.getBitsLength(this.data.length)
+}
+
+KanjiData.prototype.write = function (bitBuffer) {
+  let i
+
+  // In the Shift JIS system, Kanji characters are represented by a two byte combination.
+  // These byte values are shifted from the JIS X 0208 values.
+  // JIS X 0208 gives details of the shift coded representation.
+  for (i = 0; i < this.data.length; i++) {
+    let value = Utils.toSJIS(this.data[i])
+
+    // For characters with Shift JIS values from 0x8140 to 0x9FFC:
+    if (value >= 0x8140 && value <= 0x9FFC) {
+      // Subtract 0x8140 from Shift JIS value
+      value -= 0x8140
+
+    // For characters with Shift JIS values from 0xE040 to 0xEBBF
+    } else if (value >= 0xE040 && value <= 0xEBBF) {
+      // Subtract 0xC140 from Shift JIS value
+      value -= 0xC140
+    } else {
+      throw new Error(
+        'Invalid SJIS character: ' + this.data[i] + '\n' +
+        'Make sure your charset is UTF-8')
+    }
+
+    // Multiply most significant byte of result by 0xC0
+    // and add least significant byte to product
+    value = (((value >>> 8) & 0xff) * 0xC0) + (value & 0xff)
+
+    // Convert result to a 13-bit binary string
+    bitBuffer.put(value, 13)
+  }
+}
+
+module.exports = KanjiData