Remove unused scripts and update documentation

[wycats]

Summary

This PR removes non-working scripts and their references from the codebase, cleaning up package.json and updating documentation to reflect the actual working commands.

Changes

• Removed 7 non-working scripts from package.json:

  • browserstack:connect
  • browserstack:disconnect
  • browserstack:results
  • build:control
  • build:flags
  • test:browserstack
  • test:smoke

• Removed unused dependencies:

  • ember-cli-browserstack
  • ember-cli

• Updated README.md to use correct test commands:

  • Changed ember test --server → pnpm start
  • Updated test instructions to reflect current tooling

Test plan

• Verified all referenced scripts were removed or non-existent
• Ran CI preparation commands (pnpm lint:fix, pnpm repo:update:conventions, pnpm repo:update:metadata)
• Checked for any remaining references to removed scripts
• Confirmed working commands still function properly

[github-actions]

	This PR	main
Dev	588K └─┬ . 169K ├── runtime 160K ├── syntax 100K ├── compiler 58K ├── opcode-compiler 27K ├── manager 24K ├── validator 11K ├── program 8.9K ├── reference 7.2K ├── destroyable 6.3K ├── util 4.3K ├── node 3.4K ├── global-context 2.5K ├── wire-format 1.0K ├── vm 969B ├── encoder 844B ├── vm-babel-plugins 606B └── owner	588K └─┬ . 169K ├── runtime 160K ├── syntax 100K ├── compiler 58K ├── opcode-compiler 27K ├── manager 24K ├── validator 11K ├── program 8.9K ├── reference 7.2K ├── destroyable 6.3K ├── util 4.3K ├── node 3.4K ├── global-context 2.5K ├── wire-format 1.0K ├── vm 969B ├── encoder 844B ├── vm-babel-plugins 606B └── owner
Prod	231K └─┬ . 70K ├── syntax 63K ├── runtime 48K ├── compiler 18K ├── opcode-compiler 7.9K ├── manager 5.1K ├── validator 4.8K ├── program 3.6K ├── reference 2.4K ├── util 2.1K ├── node 1.6K ├── wire-format 1.5K ├── destroyable 737B ├── vm 594B ├── global-context 516B ├── encoder 469B ├── vm-babel-plugins 155B └── owner	231K └─┬ . 70K ├── syntax 63K ├── runtime 48K ├── compiler 18K ├── opcode-compiler 7.9K ├── manager 5.1K ├── validator 4.8K ├── program 3.6K ├── reference 2.4K ├── util 2.1K ├── node 1.6K ├── wire-format 1.5K ├── destroyable 737B ├── vm 594B ├── global-context 516B ├── encoder 469B ├── vm-babel-plugins 155B └── owner