Document viewer test commands

Add IfcOpenShell-Python and IfcViewer test-running documentation, including desktop CTest targets and web Playwright smoke tests. Move the web test README content into the Sphinx docs.\n\nGenerated with the assistance of an AI coding tool.

src/ifcviewer-web/tests/README.md

@@ -1,45 +0,0 @@
-# Web smoke tests
-
-Headless-browser smoke tests for the WebGPU/Emscripten ifcviewer build.
-They load the built page in a real Chrome, wait for wgpu init, and assert
-the embedded sample **renders non-blank**, an **orbit drag changes the
-framebuffer**, and **no uncaptured WebGPU errors** are logged. Every web
-bring-up bug so far (blank render, error-buffer cascade, an overlay
-swallowing mouse input) is this shape.
-
-## Prerequisites
-
-- The web build must exist at `build-web/` (repo root):
-  ```sh
-  source /path/to/emsdk_env.sh
-  emcmake cmake -S src/ifcviewer-web -B build-web
-  ninja -C build-web IfcViewerWeb
-  ```
-- Node + a system Chrome (`google-chrome-stable`). The config uses
-  `channel: 'chrome'`, so you do **not** need `npx playwright install`.
-
-## Run
-
-```sh
-cd src/ifcviewer-web/tests
-npm install          # one-time: pulls @playwright/test
-npm test
-```
-
-`serve.mjs` statically serves `build-web` on :8124 (override with
-`WEB_BUILD_DIR=/path PORT=...`). Playwright starts it automatically.
-
-## Headless / CI
-
-WebGPU + headless on Linux is finicky, so the default config runs
-**headed** against the machine's real GPU. On a headless box:
-
-```sh
-xvfb-run -a npm test
-```
-
-For a GPU-less runner, flip `headless: true` in
-`playwright.config.mjs` and provide a SwiftShader Vulkan ICD
-(`VK_ICD_FILENAMES=.../vk_swiftshader_icd.json`) plus
-`--use-angle=swiftshader`. Browser WebGPU over SwiftShader is slow but
-adequate for a render-non-blank assertion.