fix: Solving problem that only limited number of CEF layers work in Docker environment. Fixes #1675

[toontoet]

When running CasparCG in headless mode in Docker only limited number of html layers work (2 with gpu enabled, 4 without gpu).

This fix increases the number of CEF processes and disables shared memory, which migh be to limited in Docker environments.

// FIX 1: Increase renderer process limit to support more concurrent HTML layers
// Default CEF limit is ~3-6 processes, which limits HTML layer count
command_line->AppendSwitchWithValue("renderer-process-limit", "20");

// FIX 2: Prevent shared memory exhaustion on Linux (especially in Docker)
// /dev/shm is limited to 64MB by default in most Docker containers
command_line->AppendSwitch("disable-dev-shm-usage");

[Julusian]

From reading puppeteer/puppeteer#1834 I am not sure that the dev-shm change is a good idea.

Instead maybe it would be enough to document that when running the docker image --shm-size=256m argument should be used. Perhaps some testing is needed to choose a suitable value for that, or leave that up to the user.