Restructure the Python API and internals around composable namespaces and
a standalone transport/endpoint layer. Bump to 0.12.0.
Python API:
- Replace flat methods (b.tabs_list(), b.group_list()) with namespaces:
b.nav, b.tabs, b.groups, b.windows, b.dom, b.extract, b.page, b.storage,
b.cookies, b.session, b.perf, b.extension.
- Shrink browser_cli/__init__.py to a thin composition root; move all
behaviour into browser_cli/sdk/ (one module per namespace + factories,
base, routing).
Internals:
- Add browser_cli/transport.py and remote_transport.py to isolate IPC from
command logic; client.py now delegates instead of owning transport.
- Add browser_cli/endpoints.py for endpoint resolution and
browser_cli/errors.py for shared error types.
- Extract markdown rendering into browser_cli/markdown.py (out of extract).
- Add USER_AGENT to version_manager.
Tooling & tests:
- Add justfile with common dev tasks.
- Update CLI commands and demo to the namespaced API.
- Rework tests for the new layout; add test_transport.py and
test_refactor_boundaries.py to lock in module boundaries.
BREAKING CHANGE: flat API methods are removed in favour of namespaces
(e.g. b.tabs_list() -> b.tabs.list(), b.group_list() -> b.groups.list()).
