Phase 1 of #5963: reorganize building blocks (buffer, parser, input,
data, and shared utilities) under common/primitives/. Runtime code
(services, public API, CoreTerminal, InputHandler) stays in place.
Update import paths across browser, headless, addons, and tests.
Add TypeScript path mappings so common/* aliases resolve primitives
first, then the common root.
Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>
