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/png.js

@@ -0,0 +1,194 @@
+"use strict";
+
+let util = require("util");
+let Stream = require("stream");
+let Parser = require("./parser-async");
+let Packer = require("./packer-async");
+let PNGSync = require("./png-sync");
+
+let PNG = (exports.PNG = function (options) {
+  Stream.call(this);
+
+  options = options || {}; // eslint-disable-line no-param-reassign
+
+  // coerce pixel dimensions to integers (also coerces undefined -> 0):
+  this.width = options.width | 0;
+  this.height = options.height | 0;
+
+  this.data =
+    this.width > 0 && this.height > 0
+      ? Buffer.alloc(4 * this.width * this.height)
+      : null;
+
+  if (options.fill && this.data) {
+    this.data.fill(0);
+  }
+
+  this.gamma = 0;
+  this.readable = this.writable = true;
+
+  this._parser = new Parser(options);
+
+  this._parser.on("error", this.emit.bind(this, "error"));
+  this._parser.on("close", this._handleClose.bind(this));
+  this._parser.on("metadata", this._metadata.bind(this));
+  this._parser.on("gamma", this._gamma.bind(this));
+  this._parser.on(
+    "parsed",
+    function (data) {
+      this.data = data;
+      this.emit("parsed", data);
+    }.bind(this)
+  );
+
+  this._packer = new Packer(options);
+  this._packer.on("data", this.emit.bind(this, "data"));
+  this._packer.on("end", this.emit.bind(this, "end"));
+  this._parser.on("close", this._handleClose.bind(this));
+  this._packer.on("error", this.emit.bind(this, "error"));
+});
+util.inherits(PNG, Stream);
+
+PNG.sync = PNGSync;
+
+PNG.prototype.pack = function () {
+  if (!this.data || !this.data.length) {
+    this.emit("error", "No data provided");
+    return this;
+  }
+
+  process.nextTick(
+    function () {
+      this._packer.pack(this.data, this.width, this.height, this.gamma);
+    }.bind(this)
+  );
+
+  return this;
+};
+
+PNG.prototype.parse = function (data, callback) {
+  if (callback) {
+    let onParsed, onError;
+
+    onParsed = function (parsedData) {
+      this.removeListener("error", onError);
+
+      this.data = parsedData;
+      callback(null, this);
+    }.bind(this);
+
+    onError = function (err) {
+      this.removeListener("parsed", onParsed);
+
+      callback(err, null);
+    }.bind(this);
+
+    this.once("parsed", onParsed);
+    this.once("error", onError);
+  }
+
+  this.end(data);
+  return this;
+};
+
+PNG.prototype.write = function (data) {
+  this._parser.write(data);
+  return true;
+};
+
+PNG.prototype.end = function (data) {
+  this._parser.end(data);
+};
+
+PNG.prototype._metadata = function (metadata) {
+  this.width = metadata.width;
+  this.height = metadata.height;
+
+  this.emit("metadata", metadata);
+};
+
+PNG.prototype._gamma = function (gamma) {
+  this.gamma = gamma;
+};
+
+PNG.prototype._handleClose = function () {
+  if (!this._parser.writable && !this._packer.readable) {
+    this.emit("close");
+  }
+};
+
+PNG.bitblt = function (src, dst, srcX, srcY, width, height, deltaX, deltaY) {
+  // eslint-disable-line max-params
+  // coerce pixel dimensions to integers (also coerces undefined -> 0):
+  /* eslint-disable no-param-reassign */
+  srcX |= 0;
+  srcY |= 0;
+  width |= 0;
+  height |= 0;
+  deltaX |= 0;
+  deltaY |= 0;
+  /* eslint-enable no-param-reassign */
+
+  if (
+    srcX > src.width ||
+    srcY > src.height ||
+    srcX + width > src.width ||
+    srcY + height > src.height
+  ) {
+    throw new Error("bitblt reading outside image");
+  }
+
+  if (
+    deltaX > dst.width ||
+    deltaY > dst.height ||
+    deltaX + width > dst.width ||
+    deltaY + height > dst.height
+  ) {
+    throw new Error("bitblt writing outside image");
+  }
+
+  for (let y = 0; y < height; y++) {
+    src.data.copy(
+      dst.data,
+      ((deltaY + y) * dst.width + deltaX) << 2,
+      ((srcY + y) * src.width + srcX) << 2,
+      ((srcY + y) * src.width + srcX + width) << 2
+    );
+  }
+};
+
+PNG.prototype.bitblt = function (
+  dst,
+  srcX,
+  srcY,
+  width,
+  height,
+  deltaX,
+  deltaY
+) {
+  // eslint-disable-line max-params
+
+  PNG.bitblt(this, dst, srcX, srcY, width, height, deltaX, deltaY);
+  return this;
+};
+
+PNG.adjustGamma = function (src) {
+  if (src.gamma) {
+    for (let y = 0; y < src.height; y++) {
+      for (let x = 0; x < src.width; x++) {
+        let idx = (src.width * y + x) << 2;
+
+        for (let i = 0; i < 3; i++) {
+          let sample = src.data[idx + i] / 255;
+          sample = Math.pow(sample, 1 / 2.2 / src.gamma);
+          src.data[idx + i] = Math.round(sample * 255);
+        }
+      }
+    }
+    src.gamma = 0;
+  }
+};
+
+PNG.prototype.adjustGamma = function () {
+  PNG.adjustGamma(this);
+};