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/pngjs/lib/packer.js

@@ -0,0 +1,129 @@
+"use strict";
+
+let constants = require("./constants");
+let CrcStream = require("./crc");
+let bitPacker = require("./bitpacker");
+let filter = require("./filter-pack");
+let zlib = require("zlib");
+
+let Packer = (module.exports = function (options) {
+  this._options = options;
+
+  options.deflateChunkSize = options.deflateChunkSize || 32 * 1024;
+  options.deflateLevel =
+    options.deflateLevel != null ? options.deflateLevel : 9;
+  options.deflateStrategy =
+    options.deflateStrategy != null ? options.deflateStrategy : 3;
+  options.inputHasAlpha =
+    options.inputHasAlpha != null ? options.inputHasAlpha : true;
+  options.deflateFactory = options.deflateFactory || zlib.createDeflate;
+  options.bitDepth = options.bitDepth || 8;
+  // This is outputColorType
+  options.colorType =
+    typeof options.colorType === "number"
+      ? options.colorType
+      : constants.COLORTYPE_COLOR_ALPHA;
+  options.inputColorType =
+    typeof options.inputColorType === "number"
+      ? options.inputColorType
+      : constants.COLORTYPE_COLOR_ALPHA;
+
+  if (
+    [
+      constants.COLORTYPE_GRAYSCALE,
+      constants.COLORTYPE_COLOR,
+      constants.COLORTYPE_COLOR_ALPHA,
+      constants.COLORTYPE_ALPHA,
+    ].indexOf(options.colorType) === -1
+  ) {
+    throw new Error(
+      "option color type:" + options.colorType + " is not supported at present"
+    );
+  }
+  if (
+    [
+      constants.COLORTYPE_GRAYSCALE,
+      constants.COLORTYPE_COLOR,
+      constants.COLORTYPE_COLOR_ALPHA,
+      constants.COLORTYPE_ALPHA,
+    ].indexOf(options.inputColorType) === -1
+  ) {
+    throw new Error(
+      "option input color type:" +
+        options.inputColorType +
+        " is not supported at present"
+    );
+  }
+  if (options.bitDepth !== 8 && options.bitDepth !== 16) {
+    throw new Error(
+      "option bit depth:" + options.bitDepth + " is not supported at present"
+    );
+  }
+});
+
+Packer.prototype.getDeflateOptions = function () {
+  return {
+    chunkSize: this._options.deflateChunkSize,
+    level: this._options.deflateLevel,
+    strategy: this._options.deflateStrategy,
+  };
+};
+
+Packer.prototype.createDeflate = function () {
+  return this._options.deflateFactory(this.getDeflateOptions());
+};
+
+Packer.prototype.filterData = function (data, width, height) {
+  // convert to correct format for filtering (e.g. right bpp and bit depth)
+  let packedData = bitPacker(data, width, height, this._options);
+
+  // filter pixel data
+  let bpp = constants.COLORTYPE_TO_BPP_MAP[this._options.colorType];
+  let filteredData = filter(packedData, width, height, this._options, bpp);
+  return filteredData;
+};
+
+Packer.prototype._packChunk = function (type, data) {
+  let len = data ? data.length : 0;
+  let buf = Buffer.alloc(len + 12);
+
+  buf.writeUInt32BE(len, 0);
+  buf.writeUInt32BE(type, 4);
+
+  if (data) {
+    data.copy(buf, 8);
+  }
+
+  buf.writeInt32BE(
+    CrcStream.crc32(buf.slice(4, buf.length - 4)),
+    buf.length - 4
+  );
+  return buf;
+};
+
+Packer.prototype.packGAMA = function (gamma) {
+  let buf = Buffer.alloc(4);
+  buf.writeUInt32BE(Math.floor(gamma * constants.GAMMA_DIVISION), 0);
+  return this._packChunk(constants.TYPE_gAMA, buf);
+};
+
+Packer.prototype.packIHDR = function (width, height) {
+  let buf = Buffer.alloc(13);
+  buf.writeUInt32BE(width, 0);
+  buf.writeUInt32BE(height, 4);
+  buf[8] = this._options.bitDepth; // Bit depth
+  buf[9] = this._options.colorType; // colorType
+  buf[10] = 0; // compression
+  buf[11] = 0; // filter
+  buf[12] = 0; // interlace
+
+  return this._packChunk(constants.TYPE_IHDR, buf);
+};
+
+Packer.prototype.packIDAT = function (data) {
+  return this._packChunk(constants.TYPE_IDAT, data);
+};
+
+Packer.prototype.packIEND = function () {
+  return this._packChunk(constants.TYPE_IEND, null);
+};