Spoof navigator.maxTouchPoints from config

[nxbdev]

Related Issue

Closes #696

Description

navigator.maxTouchPoints was already a recognized config property (settings/properties.json declares it) but nothing read it, so it always reported 0 on a desktop build regardless of the config. Under a Firefox-for-Android user agent that 0 is a mobile-detection tell — a real phone reports 5, and Firefox's RFP path only ever collapses the value to 0 (MaxTouchPointsCollapse), with no path to a phone value without an explicit override.

This adds the standard MaskConfig early-return at the top of Navigator::MaxTouchPoints, matching how every other navigator/screen property is spoofed (GetPlatform, GetOscpu, HardwareConcurrency, nsScreen::PixelDepth, …):

if (auto value = MaskConfig::GetUint32("navigator.maxTouchPoints")) {
  return value.value();
}

Navigator.cpp already includes MaskConfig.hpp via navigator-spoofing.patch, so no extra include is needed and no schema change is required. With this, navigator.maxTouchPoints in the config is honoured (e.g. 5 for a phone).

Type of Change

• Bug fix
• New feature
• Documentation update
• Other

Testing

Built and driven against the raw binary (same mechanism as build-tester/runner.py: firefox.launch(executable_path=…, env={CAMOU_CONFIG})), reading navigator.maxTouchPoints on a page:

Case	CAMOU_CONFIG	Result
Control (no config)	—	0 (unchanged desktop default)
Phone value	{"navigator.maxTouchPoints": 5}	5
Single-touch	{"navigator.maxTouchPoints": 1}	1

• Patch applies cleanly against the current main (Firefox 152.0.4, beta.28) — patching file dom/base/Navigator.cpp, no rejects/fuzz.
• Verified on a linux/arm64 build.

Fingerprint Report

Fingerprint report

build-tester score/screenshot to be attached once the current beta.28 arm64 build completes — this PR is opened as a draft until then.

Checklist

• I have linked a related issue above
• My changes are focused on a single logical change
• I have added testing instructions which include the desired result
• Service tests pass (no pythonlib/ changes)
• Build test passes (score ≥ 1000, screenshot) — pending, will attach before marking ready